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44.5: Climate and the Effects of Global Climate Change - Biology

44.5: Climate and the Effects of Global Climate Change - Biology


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Skills to Develop

  • Define global climate change
  • Summarize the effects of the Industrial Revolution on global atmospheric carbon dioxide concentration
  • Describe three natural factors affecting long-term global climate
  • List two or more greenhouse gases and describe their role in the greenhouse effect

All biomes are universally affected by global conditions, such as climate, that ultimately shape each biome’s environment. Scientists who study climate have noted a series of marked changes that have gradually become increasingly evident during the last sixty years. Global climate change is the term used to describe altered global weather patterns, including a worldwide increase in temperature, due largely to rising levels of atmospheric carbon dioxide.

Climate and Weather

A common misconception about global climate change is that a specific weather event occurring in a particular region (for example, a very cool week in June in central Indiana) is evidence of global climate change. However, a cold week in June is a weather-related event and not a climate-related one. These misconceptions often arise because of confusion over the terms climate and weather.

Climate refers to the long-term, predictable atmospheric conditions of a specific area. The climate of a biome is characterized by having consistent temperature and annual rainfall ranges. Climate does not address the amount of rain that fell on one particular day in a biome or the colder-than-average temperatures that occurred on one day. In contrast, weather refers to the conditions of the atmosphere during a short period of time. Weather forecasts are usually made for 48-hour cycles. Long-range weather forecasts are available but can be unreliable.

To better understand the difference between climate and weather, imagine that you are planning an outdoor event in northern Wisconsin. You would be thinking about climate when you plan the event in the summer rather than the winter because you have long-term knowledge that any given Saturday in the months of May to August would be a better choice for an outdoor event in Wisconsin than any given Saturday in January. However, you cannot determine the specific day that the event should be held on because it is difficult to accurately predict the weather on a specific day. Climate can be considered “average” weather.

Global Climate Change

Climate change can be understood by approaching three areas of study:

  • current and past global climate change
  • causes of past and present-day global climate change
  • ancient and current results of climate change

It is helpful to keep these three different aspects of climate change clearly separated when consuming media reports about global climate change. It is common for reports and discussions about global climate change to confuse the data showing that Earth’s climate is changing with the factors that drive this climate change.

Evidence for Global Climate Change

Since scientists cannot go back in time to directly measure climatic variables, such as average temperature and precipitation, they must instead indirectly measure temperature. To do this, scientists rely on historical evidence of Earth’s past climate.

Antarctic ice cores are a key example of such evidence. These ice cores are samples of polar ice obtained by means of drills that reach thousands of meters into ice sheets or high mountain glaciers. Viewing the ice cores is like traveling backwards through time; the deeper the sample, the earlier the time period. Trapped within the ice are bubbles of air and other biological evidence that can reveal temperature and carbon dioxide data. Antarctic ice cores have been collected and analyzed to indirectly estimate the temperature of the Earth over the past 400,000 years (Figure (PageIndex{1})a). The 0 °C on this graph refers to the long-term average. Temperatures that are greater than 0 °C exceed Earth’s long-term average temperature. Conversely, temperatures that are less than 0 °C are less than Earth’s average temperature. This figure shows that there have been periodic cycles of increasing and decreasing temperature.

Before the late 1800s, the Earth has been as much as 9 °C cooler and about 3 °C warmer. Note that the graph in Figure (PageIndex{1})b shows that the atmospheric concentration of carbon dioxide has also risen and fallen in periodic cycles; note the relationship between carbon dioxide concentration and temperature. Figure (PageIndex{1})b shows that carbon dioxide levels in the atmosphere have historically cycled between 180 and 300 parts per million (ppm) by volume.

Figure 44.5.1a does not show the last 2,000 years with enough detail to compare the changes of Earth’s temperature during the last 400,000 years with the temperature change that has occurred in the more recent past. Two significant temperature anomalies, or irregularities, have occurred in the last 2000 years. These are the Medieval Climate Anomaly (or the Medieval Warm Period) and the Little Ice Age. A third temperature anomaly aligns with the Industrial Era. The Medieval Climate Anomaly occurred between 900 and 1300 AD. During this time period, many climate scientists think that slightly warmer weather conditions prevailed in many parts of the world; the higher-than-average temperature changes varied between 0.10 °C and 0.20 °C above the norm. Although 0.10 °C does not seem large enough to produce any noticeable change, it did free seas of ice. Because of this warming, the Vikings were able to colonize Greenland.

The Little Ice Age was a cold period that occurred between 1550 AD and 1850 AD. During this time, a slight cooling of a little less than 1 °C was observed in North America, Europe, and possibly other areas of the Earth. This 1 °C change in global temperature is a seemingly small deviation in temperature (as was observed during the Medieval Climate Anomaly); however, it also resulted in noticeable changes. Historical accounts reveal a time of exceptionally harsh winters with much snow and frost.

The Industrial Revolution, which began around 1750, was characterized by changes in much of human society. Advances in agriculture increased the food supply, which improved the standard of living for people in Europe and the United States. New technologies were invented and provided jobs and cheaper goods. These new technologies were powered using fossil fuels, especially coal. The Industrial Revolution starting in the early nineteenth century ushered in the beginning of the Industrial Era. When a fossil fuel is burned, carbon dioxide is released. With the beginning of the Industrial Era, atmospheric carbon dioxide began to rise (Figure (PageIndex{2})).

Current and Past Drivers of Global Climate Change

Since it is not possible to go back in time to directly observe and measure climate, scientists use indirect evidence to determine the drivers, or factors, that may be responsible for climate change. The indirect evidence includes data collected using ice cores, boreholes (a narrow shaft bored into the ground), tree rings, glacier lengths, pollen remains, and ocean sediments. The data shows a correlation between the timing of temperature changes and drivers of climate change: before the Industrial Era (pre-1780), there were three drivers of climate change that were not related to human activity or atmospheric gases. The first of these is the Milankovitch cycles. The Milankovitch cycles describe the effects of slight changes in the Earth’s orbit on Earth’s climate. The length of the Milankovitch cycles ranges between 19,000 and 100,000 years. In other words, one could expect to see some predictable changes in the Earth’s climate associated with changes in the Earth’s orbit at a minimum of every 19,000 years.

The variation in the sun’s intensity is the second natural factor responsible for climate change. Solar intensity is the amount of solar power or energy the sun emits in a given amount of time. There is a direct relationship between solar intensity and temperature. As solar intensity increases (or decreases), the Earth’s temperature correspondingly increases (or decreases). Changes in solar intensity have been proposed as one of several possible explanations for the Little Ice Age.

Finally, volcanic eruptions are a third natural driver of climate change. Volcanic eruptions can last a few days, but the solids and gases released during an eruption can influence the climate over a period of a few years, causing short-term climate changes. The gases and solids released by volcanic eruptions can include carbon dioxide, water vapor, sulfur dioxide, hydrogen sulfide, hydrogen, and carbon monoxide. Generally, volcanic eruptions cool the climate. This occurred in 1783 when volcanos in Iceland erupted and caused the release of large volumes of sulfuric oxide. This led to haze-effect cooling, a global phenomenon that occurs when dust, ash, or other suspended particles block out sunlight and trigger lower global temperatures as a result; haze-effect cooling usually extends for one or more years. In Europe and North America, haze-effect cooling produced some of the lowest average winter temperatures on record in 1783 and 1784.

Greenhouse gases are probably the most significant drivers of the climate. When heat energy from the sun strikes the Earth, gases known as greenhouse gases trap the heat in the atmosphere, as do the glass panes of a greenhouse keep heat from escaping. The greenhouse gases that affect Earth include carbon dioxide, methane, water vapor, nitrous oxide, and ozone. Approximately half of the radiation from the sun passes through these gases in the atmosphere and strikes the Earth. This radiation is converted into thermal radiation on the Earth’s surface, and then a portion of that energy is re-radiated back into the atmosphere. Greenhouse gases, however, reflect much of the thermal energy back to the Earth’s surface. The more greenhouse gases there are in the atmosphere, the more thermal energy is reflected back to the Earth’s surface. Greenhouse gases absorb and emit radiation and are an important factor in the greenhouse effect: the warming of Earth due to carbon dioxide and other greenhouse gases in the atmosphere.

Evidence supports the relationship between atmospheric concentrations of carbon dioxide and temperature: as carbon dioxide rises, global temperature rises. Since 1950, the concentration of atmospheric carbon dioxide has increased from about 280 ppm to 382 ppm in 2006. In 2011, the atmospheric carbon dioxide concentration was 392 ppm. However, the planet would not be inhabitable by current life forms if water vapor did not produce its drastic greenhouse warming effect.

Scientists look at patterns in data and try to explain differences or deviations from these patterns. The atmospheric carbon dioxide data reveal a historical pattern of carbon dioxide increasing and decreasing, cycling between a low of 180 ppm and a high of 300 ppm. Scientists have concluded that it took around 50,000 years for the atmospheric carbon dioxide level to increase from its low minimum concentration to its higher maximum concentration. However, starting recently, atmospheric carbon dioxide concentrations have increased beyond the historical maximum of 300 ppm. The current increases in atmospheric carbon dioxide have happened very quickly—in a matter of hundreds of years rather than thousands of years. What is the reason for this difference in the rate of change and the amount of increase in carbon dioxide? A key factor that must be recognized when comparing the historical data and the current data is the presence of modern human society; no other driver of climate change has yielded changes in atmospheric carbon dioxide levels at this rate or to this magnitude.

Human activity releases carbon dioxide and methane, two of the most important greenhouse gases, into the atmosphere in several ways. The primary mechanism that releases carbon dioxide is the burning of fossil fuels, such as gasoline, coal, and natural gas (Figure (PageIndex{3})). Deforestation, cement manufacture, animal agriculture, the clearing of land, and the burning of forests are other human activities that release carbon dioxide. Methane (CH4) is produced when bacteria break down organic matter under anaerobic conditions. Anaerobic conditions can happen when organic matter is trapped underwater (such as in rice paddies) or in the intestines of herbivores. Methane can also be released from natural gas fields and the decomposition that occurs in landfills. Another source of methane is the melting of clathrates. Clathrates are frozen chunks of ice and methane found at the bottom of the ocean. When water warms, these chunks of ice melt and methane is released. As the ocean’s water temperature increases, the rate at which clathrates melt is increasing, releasing even more methane. This leads to increased levels of methane in the atmosphere, which further accelerates the rate of global warming. This is an example of the positive feedback loop that is leading to the rapid rate of increase of global temperatures.

Documented Results of Climate Change: Past and Present

Scientists have geological evidence of the consequences of long-ago climate change. Modern-day phenomena such as retreating glaciers and melting polar ice cause a continual rise in sea level. Meanwhile, changes in climate can negatively affect organisms.

Geological Climate Change

Global warming has been associated with at least one planet-wide extinction event during the geological past. The Permian extinction event occurred about 251 million years ago toward the end of the roughly 50-million-year-long geological time span known as the Permian period. This geologic time period was one of the three warmest periods in Earth’s geologic history. Scientists estimate that approximately 70 percent of the terrestrial plant and animal species and 84 percent of marine species became extinct, vanishing forever near the end of the Permian period. Organisms that had adapted to wet and warm climatic conditions, such as annual rainfall of 300–400 cm (118–157 in) and 20 °C–30 °C (68 °F–86 °F) in the tropical wet forest, may not have been able to survive the Permian climate change.

Link to Learning

Watch this NASA video to discover the mixed effects of global warming on plant growth. While scientists found that warmer temperatures in the 1980s and 1990s caused an increase in plant productivity, this advantage has since been counteracted by more frequent droughts.

Present Climate Change

A number of global events have occurred that may be attributed to climate change during our lifetimes. Glacier National Park in Montana is undergoing the retreat of many of its glaciers, a phenomenon known as glacier recession. In 1850, the area contained approximately 150 glaciers. By 2010, however, the park contained only about 24 glaciers greater than 25 acres in size. One of these glaciers is the Grinnell Glacier (Figure (PageIndex{4})) at Mount Gould. Between 1966 and 2005, the size of Grinnell Glacier shrank by 40 percent. Similarly, the mass of the ice sheets in Greenland and the Antarctic is decreasing: Greenland lost 150–250 km3 of ice per year between 2002 and 2006. In addition, the size and thickness of the Arctic sea ice is decreasing.

This loss of ice is leading to increases in the global sea level. On average, the sea is rising at a rate of 1.8 mm per year. However, between 1993 and 2010 the rate of sea level increase ranged between 2.9 and 3.4 mm per year. A variety of factors affect the volume of water in the ocean, including the temperature of the water (the density of water is related to its temperature) and the amount of water found in rivers, lakes, glaciers, polar ice caps, and sea ice. As glaciers and polar ice caps melt, there is a significant contribution of liquid water that was previously frozen.

In addition to some abiotic conditions changing in response to climate change, many organisms are also being affected by the changes in temperature. Temperature and precipitation play key roles in determining the geographic distribution and phenology of plants and animals. (Phenology is the study of the effects of climatic conditions on the timing of periodic lifecycle events, such as flowering in plants or migration in birds.) Researchers have shown that 385 plant species in Great Britain are flowering 4.5 days sooner than was recorded earlier during the previous 40 years. In addition, insect-pollinated species were more likely to flower earlier than wind-pollinated species. The impact of changes in flowering date would be mitigated if the insect pollinators emerged earlier. This mismatched timing of plants and pollinators could result in injurious ecosystem effects because, for continued survival, insect-pollinated plants must flower when their pollinators are present.

Summary

The Earth has gone through periodic cycles of increases and decreases in temperature. During the past 2000 years, the Medieval Climate Anomaly was a warmer period, while the Little Ice Age was unusually cool. Both of these irregularities can be explained by natural causes of changes in climate, and, although the temperature changes were small, they had significant effects. Natural drivers of climate change include Milankovitch cycles, changes in solar activity, and volcanic eruptions. None of these factors, however, leads to rapid increases in global temperature or sustained increases in carbon dioxide. The burning of fossil fuels is an important source of greenhouse gases, which plays a major role in the greenhouse effect. Long ago, global warming resulted in the Permian extinction: a large-scale extinction event that is documented in the fossil record. Currently, modern-day climate change is associated with the increased melting of glaciers and polar ice sheets, resulting in a gradual increase in sea level. Plants and animals can also be affected by global climate change when the timing of seasonal events, such as flowering or pollination, is affected by global warming.

Glossary

clathrates
frozen chunks of ice and methane found at the bottom of the ocean
climate
long-term, predictable atmospheric conditions present in a specific area
global climate change
altered global weather patterns, including a worldwide increase in temperature, due largely to rising levels of atmospheric carbon dioxide
greenhouse effect
warming of Earth due to carbon dioxide and other greenhouse gases in the atmosphere
greenhouse gases
atmospheric gases such as carbon dioxide and methane that absorb and emit radiation, thus trapping heat in Earth’s atmosphere
haze-effect cooling
effect of the gases and solids from a volcanic eruption on global climate
Milankovitch cycles
cyclic changes in the Earth's orbit that may affect climate
solar intensity
amount of solar power energy the sun emits in a given amount of time
weather
conditions of the atmosphere during a short period of time

Effects of Climate Change

Climate change has an impact on turtle nesting sites. It alters sand temperatures, which then affects the sex of hatchlings.

Sea levels are rising and oceans are becoming warmer. Longer, more intense droughts threaten crops, wildlife and freshwater supplies. From polar bears in the Arctic to marine turtles off the coast of Africa, our planet’s diversity of life is at risk from the changing climate.

Climate change poses a fundamental threat to the places, species and people’s livelihoods WWF works to protect. To adequately address this crisis we must urgently reduce carbon pollution and prepare for the consequences of global warming, which we are already experiencing. WWF works to:

  • advance policies to fight climate change
  • engage with businesses to reduce carbon emissions
  • help people and nature adapt to a changing climate

Fortune 500 companies are acting on the climate crisis—but is it enough?

Sixty percent of Fortune 500 companies have set goals to act on the climate crisis and address energy use, yet those ambitions vary dramatically—and are not happening at the speed or scale needed to stave off the worst impacts of a warming planet, according to a new WWF report.

Blog Posts


Climate Change

Climate change and development are closely intertwined. Poor people in developing countries will feel the impacts first and worst (and already are) because of vulnerable geography and lesser ability to cope with damage from severe weather and rising sea levels. In short, climate change will be awful for everyone but catastrophic for the poor .

Preventing dangerous climate change is critical for promoting global development. And saving tropical forests is essential to doing both. Frances Seymour and Jonah Busch's new book, Why Forests? Why Now?, illustrates how today—more than ever—saving forests is more feasible, affordable, and urgent.

Historically, the responsibility for climate change, though, rested with the rich countries that emitted greenhouse gases unimpeded from the Industrial Revolution on &mdash and become rich by doing so. Now, some of the most quickly developing countries have become major emitter themselves just as all countries are compelled by the common good to reduce greenhouse gas emissions. A major challenge of reaching a global deal on climate change was to find a way for poor countries to continue developing under the planetary carbon limits that rich countries have already pushed too far. That will involve scaling up finance to deploy clean technologies, to adapt to the effects of climate change, and to compensate countries that provide the global public good of reducing emissions, especially by reducing tropical deforestation.

CGD&rsquos research and policy engagement on climate and development has had two aims: to strengthen the intellectual foundation for a viable international accord to come out of the COP 21 in Paris and to provide data, research, and analysis that policymakers and others can act upon even in the absence of an international agreement.


Climate and the Effects of Global Climate Change

All biomes are universally affected by global conditions, such as climate, that ultimately shape each biome’s environment. Scientists who study climate have noted a series of marked changes that have gradually become increasingly evident during the last sixty years. Global climate change is the term used to describe altered global weather patterns, including a worldwide increase in temperature, due largely to rising levels of atmospheric carbon dioxide.

Climate and Weather

A common misconception about global climate change is that a specific weather event occurring in a particular region (for example, a very cool week in June in central Indiana) is evidence of global climate change. However, a cold week in June is a weather-related event and not a climate-related one. These misconceptions often arise because of confusion over the terms climate and weather.

Climate refers to the long-term, predictable atmospheric conditions of a specific area. The climate of a biome is characterized by having consistent temperature and annual rainfall ranges. Climate does not address the amount of rain that fell on one particular day in a biome or the colder-than-average temperatures that occurred on one day. In contrast, weather refers to the conditions of the atmosphere during a short period of time. Weather forecasts are usually made for 48-hour cycles. Long-range weather forecasts are available but can be unreliable.

To better understand the difference between climate and weather, imagine that you are planning an outdoor event in northern Wisconsin. You would be thinking about climate when you plan the event in the summer rather than the winter because you have long-term knowledge that any given Saturday in the months of May to August would be a better choice for an outdoor event in Wisconsin than any given Saturday in January. However, you cannot determine the specific day that the event should be held on because it is difficult to accurately predict the weather on a specific day. Climate can be considered “average” weather.

Global Climate Change

Climate change can be understood by approaching three areas of study:

  • current and past global climate change
  • causes of past and present-day global climate change
  • ancient and current results of climate change

It is helpful to keep these three different aspects of climate change clearly separated when consuming media reports about global climate change. It is common for reports and discussions about global climate change to confuse the data showing that Earth’s climate is changing with the factors that drive this climate change.

Evidence for Global Climate Change

Since scientists cannot go back in time to directly measure climatic variables, such as average temperature and precipitation, they must instead indirectly measure temperature. To do this, scientists rely on historical evidence of Earth’s past climate.

Antarctic ice cores are a key example of such evidence. These ice cores are samples of polar ice obtained by means of drills that reach thousands of meters into ice sheets or high mountain glaciers. Viewing the ice cores is like traveling backward through time the deeper the sample, the earlier the time period. Trapped within the ice are bubbles of air and other biological evidence that can reveal temperature and carbon dioxide data. Antarctic ice cores have been collected and analyzed to indirectly estimate the temperature of the Earth over the past 400,000 years (Figure 1). The 0 °C on this graph refers to the long-term average. Temperatures that are greater than 0 °C exceed Earth’s long-term average temperature. Conversely, temperatures that are less than 0 °C are less than Earth’s average temperature. This figure shows that there have been periodic cycles of increasing and decreasing temperature.

Before the late 1800s, the Earth has been as much as 9 °C cooler and about 3 °C warmer. Note that the graph in Figure 1 shows that the atmospheric concentration of carbon dioxide has also risen and fallen in periodic cycles note the relationship between carbon dioxide concentration and temperature. Figure 1 shows that carbon dioxide levels in the atmosphere have historically cycled between 180 and 300 parts per million (ppm) by volume.

Figure 1: Ice at the Russian Vostok station in East Antarctica was laid down over the course 420,000 years and reached a depth of over 3,000 m. By measuring the amount of CO2 trapped in the ice, scientists have determined past atmospheric CO2 concentrations. Temperatures relative to modern day were determined from the amount of deuterium (an isotope of hydrogen) present. (credit: “CO2 and temp” by OpenStax is licensed under CC BY 4.0)

Figure 1 does not show the last 2,000 years with enough detail to compare the changes of Earth’s temperature during the last 400,000 years with the temperature change that has occurred in the more recent past. Two significant temperature anomalies, or irregularities, have occurred in the last 2000 years. These are the Medieval Climate Anomaly (or the Medieval Warm Period) and the Little Ice Age. A third temperature anomaly aligns with the Industrial Era. The Medieval Climate Anomaly occurred between 900 and 1300 AD. During this time period, many climate scientists think that slightly warmer weather conditions prevailed in many parts of the world the higher-than-average temperature changes varied between 0.10 °C and 0.20 °C above the norm. Although 0.10 °C does not seem large enough to produce any noticeable change, it did free seas of ice. Because of this warming, the Vikings were able to colonize Greenland.

The Little Ice Age was a cold period that occurred between 1550 AD and 1850 AD. During this time, a slight cooling of a little less than 1 °C was observed in North America, Europe, and possibly other areas of the Earth. This 1 °C change in global temperature is a seemingly small deviation in temperature (as was observed during the Medieval Climate Anomaly) however, it also resulted in noticeable changes. Historical accounts reveal a time of exceptionally harsh winters with much snow and frost.

The Industrial Revolution, which began around 1750, was characterized by changes in much of human society. Advances in agriculture increased the food supply, which improved the standard of living for people in Europe and the United States. New technologies were invented and provided jobs and cheaper goods. These new technologies were powered using fossil fuels, especially coal. The Industrial Revolution starting in the early nineteenth century ushered in the beginning of the Industrial Era. When fossil fuel is burned, carbon dioxide is released. With the beginning of the Industrial Era, atmospheric carbon dioxide began to rise (Figure 2).

Figure 2: The atmospheric concentration of CO2 has risen steadily since the beginning of industrialization. (credit: “CO2 1955-2005” by OpenStax is licensed under CC BY 4.0)

Current and Past Drivers of Global Climate Change

Since it is not possible to go back in time to directly observe and measure climate, scientists use indirect evidence to determine the drivers, or factors, that may be responsible for climate change. The indirect evidence includes data collected using ice cores, boreholes (a narrow shaft bored into the ground), tree rings, glacier lengths, pollen remains, and ocean sediments. The data shows a correlation between the timing of temperature changes and drivers of climate change: before the Industrial Era (pre-1780), there were three drivers of climate change that were not related to human activity or atmospheric gases. The first of these is the Milankovitch cycles. The Milankovitch cycles describe the effects of slight changes in the Earth’s orbit on Earth’s climate. The length of the Milankovitch cycles ranges between 19,000 and 100,000 years. In other words, one could expect to see some predictable changes in the Earth’s climate associated with changes in the Earth’s orbit at a minimum of every 19,000 years.

The variation in the sun’s intensity is the second natural factor responsible for climate change. Solar intensity is the amount of solar power or energy the sun emits in a given amount of time. There is a direct relationship between solar intensity and temperature. As solar intensity increases (or decreases), the Earth’s temperature correspondingly increases (or decreases). Changes in solar intensity have been proposed as one of several possible explanations for the Little Ice Age.

Finally, volcanic eruptions are a third natural driver of climate change. Volcanic eruptions can last a few days, but the solids and gases released during an eruption can influence the climate over a period of a few years, causing short-term climate changes. The gases and solids released by volcanic eruptions can include carbon dioxide, water vapor, sulfur dioxide, hydrogen sulfide, hydrogen, and carbon monoxide. Generally, volcanic eruptions cool the climate. This occurred in 1783 when volcanos in Iceland erupted and caused the release of large volumes of sulfuric oxide. This led to haze-effect cooling , a global phenomenon that occurs when dust, ash, or other suspended particles block out sunlight and trigger lower global temperatures as a result haze-effect cooling usually extends for one or more years. In Europe and North America, haze-effect cooling produced some of the lowest average winter temperatures on record in 1783 and 1784.

Greenhouse gases are probably the most significant drivers of the climate. When heat energy from the sun strikes the Earth, gases known as greenhouse gases trap the heat in the atmosphere, as do the glass panes of a greenhouse keep heat from escaping. The greenhouse gases that affect Earth include carbon dioxide, methane, water vapor, nitrous oxide, and ozone. Approximately half of the radiation from the sun passes through these gases in the atmosphere and strikes the Earth. This radiation is converted into thermal radiation on the Earth’s surface, and then a portion of that energy is re-radiated back into the atmosphere. Greenhouse gases, however, reflect much of the thermal energy back to the Earth’s surface. The more greenhouse gases there are in the atmosphere, the more thermal energy is reflected back to the Earth’s surface. Greenhouse gases absorb and emit radiation and are an important factor in the greenhouse effect: the warming of Earth due to carbon dioxide and other greenhouse gases in the atmosphere.

Evidence supports the relationship between atmospheric concentrations of carbon dioxide and temperature: as carbon dioxide rises, global temperature rises. Since 1950, the concentration of atmospheric carbon dioxide has increased from about 280 ppm to 382 ppm in 2006. In 2011, the atmospheric carbon dioxide concentration was 392 ppm. However, the planet would not be inhabitable by current life forms if water vapor did not produce its drastic greenhouse warming effect.

Scientists look at patterns in data and try to explain differences or deviations from these patterns. The atmospheric carbon dioxide data reveal a historical pattern of carbon dioxide increasing and decreasing, cycling between a low of 180 ppm and a high of 300 ppm. Scientists have concluded that it took around 50,000 years for the atmospheric carbon dioxide level to increase from its low minimum concentration to its higher maximum concentration. However, starting recently, atmospheric carbon dioxide concentrations have increased beyond the historical maximum of 300 ppm. The current increases in atmospheric carbon dioxide have happened very quickly—in a matter of hundreds of years rather than thousands of years. What is the reason for this difference in the rate of change and the amount of increase in carbon dioxide? A key factor that must be recognized when comparing the historical data and the current data is the presence of modern human society no other driver of climate change has yielded changes in atmospheric carbon dioxide levels at this rate or to this magnitude.

Human activity releases carbon dioxide and methane, two of the most important greenhouse gases, into the atmosphere in several ways. The primary mechanism that releases carbon dioxide is the burning of fossil fuels, such as gasoline, coal, and natural gas (Figure 3). Deforestation, cement manufacture, animal agriculture, the clearing of land, and the burning of forests are other human activities that release carbon dioxide. Methane (CH4) is produced when bacteria break down organic matter under anaerobic conditions. Anaerobic conditions can happen when organic matter is trapped underwater (such as in rice paddies) or in the intestines of herbivores. Methane can also be released from natural gas fields and the decomposition that occurs in landfills. Another source of methane is the melting of clathrates. Clathrates are frozen chunks of ice and methane found at the bottom of the ocean. When the water warms, these chunks of ice melt and methane is released. As the ocean’s water temperature increases, the rate at which clathrates melt is increasing, releasing even more methane. This leads to increased levels of methane in the atmosphere, which further accelerates the rate of global warming. This is an example of the positive feedback loop that is leading to the rapid rate of increase in global temperatures.

Figure 3: The burning of fossil fuels in industry and by vehicles releases carbon dioxide and other greenhouse gases into the atmosphere. (credit: “Pöllö”/Wikimedia Commons. “Pöllö” by OpenStax is licensed under CC BY 4.0)

Documented Results of Climate Change: Past and Present

Scientists have geological evidence of the consequences of long-ago climate change. Modern-day phenomena such as retreating glaciers and melting polar ice cause a continual rise in sea level. Meanwhile, changes in climate can negatively affect organisms.

Geological Climate Change

Global warming has been associated with at least one planet-wide extinction event during the geological past. The Permian extinction event occurred about 251 million years ago toward the end of the roughly 50-million-year-long geological time span known as the Permian period. This geologic time period was one of the three warmest periods in Earth’s geologic history. Scientists estimate that approximately 70 percent of the terrestrial plant and animal species and 84 percent of marine species became extinct, vanishing forever near the end of the Permian period. Organisms that had adapted to wet and warm climatic conditions, such as annual rainfall of 300–400 cm (118–157 in) and 20 °C–30 °C (68 °F–86 °F) in the tropical wet forest, may not have been able to survive the Permian climate change.

Present Climate Change

A number of global events have occurred that may be attributed to climate change during our lifetimes. Glacier National Park in Montana is undergoing the retreat of many of its glaciers, a phenomenon known as glacier recession. In 1850, the area contained approximately 150 glaciers. By 2010, however, the park contained only about 24 glaciers greater than 25 acres in size. One of these glaciers is the Grinnell Glacier (Figure 4) at Mount Gould. Between 1966 and 2005, the size of Grinnell Glacier shrank by 40 percent. Similarly, the mass of the ice sheets in Greenland and the Antarctic is decreasing: Greenland lost 150–250 km 3 of ice per year between 2002 and 2006. In addition, the size and thickness of the Arctic sea ice is decreasing.

Figure 4: The effect of global warming can be seen in the continuing retreat of Grinnel Glacier. The mean annual temperature in the park has increased 1.33 °C since 1900. The loss of a glacier results in the loss of summer meltwaters, sharply reducing seasonal water supplies and severely affecting local ecosystems. (credit: modification of work by USGS. “Grinnel Glacier retreat” by OpenStax is licensed under CC BY 4.0)

This loss of ice is leading to increases in the global sea level. On average, the sea is rising at a rate of 1.8 mm per year. However, between 1993 and 2010 the rate of sea level increase ranged between 2.9 and 3.4 mm per year. A variety of factors affect the volume of water in the ocean, including the temperature of the water (the density of water is related to its temperature) and the amount of water found in rivers, lakes, glaciers, polar ice caps, and sea ice. As glaciers and polar ice caps melt, there is a significant contribution of liquid water that was previously frozen.

In addition to some abiotic conditions changing in response to climate change, many organisms are also being affected by the changes in temperature. Temperature and precipitation play key roles in determining the geographic distribution and phenology of plants and animals. (Phenology is the study of the effects of climatic conditions on the timing of periodic lifecycle events, such as flowering in plants or migration in birds.) Researchers have shown that 385 plant species in Great Britain are flowering 4.5 days sooner than was recorded earlier during the previous 40 years. In addition, insect-pollinated species were more likely to flower earlier than wind-pollinated species. The impact of changes in flowering dates would be mitigated if the insect pollinators emerged earlier. This mismatched timing of plants and pollinators could result in injurious ecosystem effects because, for continued survival, insect-pollinated plants must flower when their pollinators are present.

Summary

The Earth has gone through periodic cycles of increases and decreases in temperature. During the past 2000 years, the Medieval Climate Anomaly was a warmer period, while the Little Ice Age was unusually cool. Both of these irregularities can be explained by natural causes of changes in climate, and, although the temperature changes were small, they had significant effects. Natural drivers of climate change include Milankovitch cycles, changes in solar activity, and volcanic eruptions. None of these factors, however, leads to rapid increases in global temperature or sustained increases in carbon dioxide. The burning of fossil fuels is an important source of greenhouse gases, which plays a major role in the greenhouse effect. Long ago, global warming resulted in the Permian extinction: a large-scale extinction event that is documented in the fossil record. Currently, modern-day climate change is associated with the increased melting of glaciers and polar ice sheets, resulting in a gradual increase in sea level. Plants and animals can also be affected by global climate change when the timing of seasonal events, such as flowering or pollination, is affected by global warming.


Discussion

Neither climate change nor global interconnectivity show signs of abating 12, 29 . As such, Chikungunya is likely to remain an important public health preparedness priority in regions where it has already been introduced as well as in regions at the fringes of its current distribution.

This is, to our knowledge, the first global study on spatio-temporal patterns of potential Chikungunya transmission using the RCP 4.5 and RCP 8.5 climate change scenarios. The modelling algorithms applied in this study to generate spatially explicit hazard maps for established climate change scenarios and time steps are based upon a correlative niche modelling approach to identify global regions that may be climatically favourable for Chikungunya transmission.

There are, broadly speaking, two key approaches for modelling vector-borne diseases. One is mechanistic modelling, which requires a detailed parameterization of numerous intricate biological processes, such as mosquito breeding and survival rates, mosquito biting rates, and the extrinsic incubation period. Although these models are thorough and based upon clear biological processes, there are important limitations to this approach. One relates to the unavailability of empirical data for the parameterization of biological processes, which may be a particular challenge for diseases such as Chikungunya which are relatively understudied. Another limitation is that modelling biological processes alone may tend to lead to overestimations (i.e. false positives) of the impacts of climate change, because they do not account for socioeconomic contexts or potential public health control measures 30,31,32 . In contrast, correlative modelling approaches such as the one presented here have an advantage in situations in which biological processes are incompletely parameterized 33 , as the method obviates the need to model the many unknown parameters that affect the interactions between Chikungunya virus, its mosquito vectors and humans. The focus instead is a priori on the climatic characteristics that are common to global regions that have recorded Chikungunya transmission.

Nonetheless, as with all modelling approaches, there are limitations to correlative niche modelling as well. First, vector-borne disease transmission is very complex, involving drivers across a wide range of socioeconomic and climatic variables. In the models presented here, socioeconomic vulnerabilities and related driving forces of Chikungunya transmission are intentionally excluded because the whole array and the diversity of processes in different continents and countries cannot be feasibly modelled. The models may nonetheless be indirectly affected by socio-economic and public health factors which may either protect against or exacerbate Chikungunya transmission. For example, there is historic evidence for Chikungunya occurring in relatively cool sub-tropical climates (such as Charleston, South Carolina, USA) 34 , but due to vector control and other measures current cases in those regions are sparse. Similarly, our models do not attempt to consider future adaptive measures that might be undertaken to mitigate the risk of Chikungunya transmission. Instead, we present models that identify hazard through the combination of climatic suitability and population density (right panels, Figs 1–5 and S1–S5).

A second limitation relates to the climatic input data. While the climate data used for the baseline model and future projections represent the same climatic parameters (such as “minimum temperature of the coldest month”), the underlying input data and methods are different. The Worldclim dataset for the baseline model is interpolated from data measured by weather stations 28 , whereas the data used for future projections comes from global climate models (GCM) that simulate physical processes in the atmosphere numerically. Although the approach of using those two data sources together has been widely applied, the comparability between baseline and future models is restricted nevertheless.

Finally, although calculating values for the mean climatic suitability from the climatic projections obtained from 5 different GCMs generally helps to increase confidence in the globally detected patterns (see Fig. S6 for standard deviations), small-scale differences in projected climate may lead to local under-estimations of climatic suitability (Fig. S7). Global models are only capable of displaying large-scale patterns and are best used for identifying areas of concern which could be further examined by subsequent smaller-scale models that would be better capable of representing locally relevant factors, such as the abundance of mosquito breeding sites, efforts in vector control, and local public health surveillance, preparedness, and response measures related to Chikungunya.

In comparing our baseline models with other recently-published works on Chikungunya 22, 35 and its vectors 36 , there are general agreements at large scales, albeit with smaller-scale differences. In Oceania, for example, our model (Fig. 1), the Chikungunya model by Nsoesie et al. 22 as well as the vector models by Kraemer et al. 36 all cover the same general suitability areas between India, southern Japan and northern Australia. However, the model by Nsoesie et al. 22 predicts comparably low environmental suitability in India (from where large numbers of Chikungunya cases have been reported, compare Fig. S8 and supplementary data), south-eastern China, southern Japan and northern Australia. When compared to the models by Kraemer et al. 36 , our model corresponds more closely to the Ae. aegypti model than the Ae. albopictus model for this region, but with lesser projected climatic potential for Chikungunya in the northern parts of India, where Chikungunya cases are currently less common (Fig. S8).

In Sub-Saharan Africa, all of these models predict high suitability in the area between roughly Senegal, the Ethiopian Plateau, the Congo Basin and the mouth of the Congo River, as well as Madagascar and a strip along the eastern coast between Kenya and Swaziland. Suitable areas also include parts of Angola and Zambia in the two vector models by Kraemer et al. 36 , while our model (Fig. 2) and the Ae. aegypti model 36 predict higher suitability closer to the Sahara Desert in the north.

In Central America, all models agree on the Caribbean Islands as well as the coastal regions of the mainland being suitable for Chikungunya transmission. With the exception of the models by Mordecai et al. 35 , all models agree on Chikungunya or its vectors, respectively, being largely absent from the Savannahs and Steppes of inland-Mexico.

In North America, our model predicts relatively low over-all climatic potential for Chikungunya transmission. However, the areas of relatively higher suitability closely match the combined patterns of Ae. aegypti and Ae. albopictus distribution in the United States, as represented by the models by Kraemer et al. 36 While the model by Nsoesie et al. 22 appears to predict the US to be less suitable than all other models, those produced by Mordecai et al. 35 predict 3 weeks of potential transmission areas as far north as Edmonton (Canada). The latter is probably due to the omission of low-temperature effects on mosquito survival as a modelling parameter, as even short periods of hard frost can significantly increase mortality of diapausing and non-diapausing Aedes eggs 37 .

In South America, all models covering the region predict a wide-spread potential for Chikungunya and its vectors respectively. Complete absence of Chikungunya is predicted for the Andes, Atacama Desert and Patagonia by all models. The mechanistic models of Mordecai et al. 35 deviate from all other models by suggesting up to 5 consecutive months of potential transmission in the dry desert climates south of Trelew, Argentina as well as in a narrow strip along the western coast as far south as Los Ángeles, Chile. This is most likely due to the omission of precipitation and low-temperature limits as explanatory variables, as the very dry climate reduces availability of breeding sites for the vectors. In all other regions, Chikungunya transmission is possible in all models, though the distribution of relatively high and low suitability differs vastly among models.

In Europe, our baseline model (Fig. 5) appears to predict the locations of the recorded outbreaks in Italy and France much more accurately than the model by Nsoesie et al. 22 When compared with the Ae. albopictus model from Kraemer et al. 36 , areas of very high climatic potential for Chikungunya transmission are more locally constrained in our model. Their vector model identifies suitable climatic conditions in Portugal and south-western Spain as well as nearly all coastal regions along the Mediterranean Sea. While many of these regions are not identified as highly climatically suitable areas for Chikungunya transmission in our model, it must be noted that they still represent a raised potential for Chikungunya transmission and should not be interpreted as low-risk areas.

To summarise, the two niche-type models based on Chikungunya occurrences, namely ours and the one by Nsoesie et al. 22 , anticipate less Chikungunya transmission in temperate regions than the other ones. This may simply be a surveillance artefact: current records of Chikungunya transmission in these areas are comparably sparse, possibly because Chikungunya is not generally expected in these regions by public health practitioners, which would mean that there is a gap in surveillance and, consequently, that our models under-estimate Chikungunya hazard in these areas. Conversely, perhaps more plausibly, it could mean that there may be additional effects of temperature that prevent Chikungunya transmission but not vector presence. It is important to note that while it is generally assumed that the Extrinsic Incubation Period (EIP) for Chikungunya is shorter than for Dengue, there are to our knowledge no systematic laboratory or field studies on how the EIP for Chikungunya changes at moderate to low temperatures. Even for Dengue, which is relatively well-studied, data on this is sparse and partially problematic 38 .

The novel models presented here demonstrate projected shifts in the climatic suitability for Chikungunya globally over the next century to identify regions with comparatively high hazards of Chikungunya transmission. The models project a net global increase in climate suitability for Chikungunya transmission by 2100, albeit with some important exceptions. Given the continued expectation for rapid global viral spread of Chikungunya alongside significant projected climatic changes over the next century, the models presented here can substantially contribute to integrated planning processes linking climate change adaptation with public health preparedness for mosquito-borne diseases.


Effects of climate change on humans

We are already experiencing the effects of a changing climate. Rising sea levels cause problems for people around the world. Nearly 4 in 10 people (39%) live within 100 kilometres from a shoreline and are at risk of flooding if sea levels continue to rise. 600 million of these people live in a &aposlow-level coastal zone&apos, and 200 million on a coastal flood plain.

Even if we cut emissions, sea levels will continue to rise until the year 2100. But, if we reduce emissions enough, we can slow the rate of increase. Many people will have to leave their homes, but the number will vary depending on how we act, by reducing global emissions and improving flood defences.

Floods can also happen when heavy rainfall overwhelms drainage systems or bursts river banks. In heavily concreted urban areas and cities, the effect is more severe because the water cannot sink directly into the soil. Flooding causes severe damage to buildings and transportation, which can be very costly and hard to recover. 

As our climate warms and rainfall patterns change, it may be harder to grow enough food in some areas. The climate will change which crops can grow in different regions. Some places may be able to grow new crops, but many places will experience reduced crop production, especially in hotter countries. 

Colder countries are likely to see higher yields because there will be a longer growing season and higher carbon dioxide concentrations. However, these effects may not last if warming continues in the longer term. More extreme weather events could also disrupt access to food, impacting transport from farms to shops, which can affect vulnerable people.

As you can see, climate change has a lot of effects, and they impact people around the world in different ways. The level of impact depends on the climate of the area and the wealth of the country. Climate change effects are &aposstress multipliers&apos, which means that they often make existing problems more severe. 

Let&aposs look at heatwaves, for example. We expect most regions will experience more intense heatwaves. In countries that are already hot, the human heat stress limits will be exceeded more often, which is dangerous. 

As another example, an increase in flooding is another danger. Countries that flood regularly, such as Bangladesh, are expected to see even more regular floods, putting more communities at risk.

This graph from Munich RE shows events causing loss are becoming more frequent.

If our climate continues to change, many parts of the world will become more challenging places to live. People may have to leave their homes. Climate is just one of many factors that influences human migration, but it will play an increasing role in the future. 


International Impacts

Climate change is very likely to affect food security at the global, regional, and local level. Climate change can disrupt food availability, reduce access to food, and affect food quality. [14] For example, projected increases in temperatures, changes in precipitation patterns, changes in extreme weather events, and reductions in water availability may all result in reduced agricultural productivity. Increases in the frequency and severity extreme weather events can also interrupt food delivery, and resulting spikes in food prices after extreme events are expected to be more frequent in the future. Increasing temperatures can contribute to spoilage and contamination.

Internationally, these effects of climate change on agriculture and food supply are likely to be similar to those seen in the United States. However, other stressors such as population growth may magnify the effects of climate change on food security. In developing countries, adaptation options like changes in crop-management or ranching practices, or improvements to irrigation are more limited than in the United States and other industrialized nations.

Any climate-related disturbance to food distribution and transport, internationally or domestically, may have significant impacts not only on safety and quality but also on food access. For example, the food transportation system in the United States frequently moves large volumes of grain by water. In the case of an extreme weather event affecting a waterway, there are few, if any, alternate pathways for transport. High temperatures and a shortage of rain in the summer of 2012 led to one of the most severe summer droughts the nation has seen and posed serious impacts to the Mississippi River watershed, a major transcontinental shipping route for Midwestern agriculture. This drought resulted in significant food and economic losses due to reductions in barge traffic, the volume of goods carried, and the number of Americans employed by the tugboat industry. The 2012 drought was immediately followed by flooding throughout the Mississippi in the spring of 2013, which also resulted in disruptions of barge traffic and food transport. [3] Transportation changes such as these reduce the ability of farmers to export their grains to international markets, and can affect global food prices.

Impacts to the global food supply concern the United States because food shortages can cause humanitarian crises and national security concerns. They also can increase domestic food prices.

References

[1] USGCRP (2014). Hatfield, J., G. Takle, R. Grotjahn, P. Holden, R. C. Izaurralde, T. Mader, E. Marshall, and D. Liverman, 2014: Ch. 6: Agri­culture. Climate Change Impacts in the United States: The Third National Climate Assessment, J. M. Melillo, Terese (T.C.) Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program, 150-174.

[3] USGCRP (2014). Ziska, L., A. Crimmins, A. Auclair, S. DeGrasse, J.F. Garofalo, A.S. Khan, I. Loladze, A.A. Pérez de León, A. Showler, J. Thurston, and I. Walls, 2016: Ch. 7: Food Safety, Nutrition, and Distribution. The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. U.S. Global Change Research Program, Washington, DC, 189–216.

[6] CCSP (2008). The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity in the United States. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. Backlund, P., A. Janetos, D. Schimel, J. Hatfield, K. Boote, P. Fay, L. Hahn, C. Izaurralde, B.A. Kimball, T. Mader, J. Morgan, D. Ort, W. Polley, A. Thomson, D. Wolfe, M. Ryan, S. Archer, R. Birdsey, C. Dahm, L. Heath, J. Hicke, D. Hollinger, T. Huxman, G. Okin, R. Oren, J. Randerson, W. Schlesinger, D. Lettenmaier, D. Major, L. Poff, S. Running, L. Hansen, D. Inouye, B.P. Kelly, L Meyerson, B. Peterson, and R. Shaw. U.S. Environmental Protection Agency, Washington, DC, USA.

[7] NOAA (2014). National Marine Fisheries Service. Fisheries of the United States, 2014. NOAA Current Fishery Statistics No. 2014.


Climate change

The directory provides links to web-accessible resources in categories of relevance to policymaking. Links to climate change portals of UNEP/WHO and other UN agencies are in Section 9. Selected links to other organizations, e.g. academic/research institutes, government and civil society are in Section 10.

Policy brief

Since 1988, the United Nations Intergovernmental Panel on Climate Change (IPCC) has reviewed scientific research, and provided governments with summaries and advice on climate problems. In its most recent report, the IPCC concludes that the average temperature of the earth's surface has risen by 0.6 °C since the late 1800s. It is expected to increase by another 1.4–5.8 °C by the year 2100 – a rapid and profound change. Even if the minimum predicted increase takes place, it will be larger than any century-long trend in the last 10 000 years. The principal reason for the global increase in temperatures is a century and a half of industrialization, with the burning of ever-greater quantities of oil, gasoline, and coal the cutting of forests and use of certain farming methods.

Climatic changes already are estimated to cause over 150,000 deaths annually.

That estimate includes deaths as a result of extreme weather conditions, which may be occurring with increased frequency. Changes in temperature and rainfall conditions also may influence transmission patterns for many diseases, including water-related diseases, such as diarrhoea, and vector-borne infections, including malaria. Finally, climate change may affect patterns of food production, which in turn can have health impacts in terms of rates of malnutrition. There is further evidence that unmitigated greenhouse gas emissions would increase disease burdens in the coming decades. The risks are concentrated in the poorest populations, who have contributed the least to the problem of greenhouse gas emissions.

Over a decade ago, most countries joined an international treaty – the United Nations Framework Convention on Climate Change – to begin to consider what can be done to reduce global warming and to cope with whatever temperature increases are inevitable.

In 1997, the Kyoto Protocol, which has more powerful (and legally binding) measures, was developed by governments as an addition to the treaty. This protocol came into force on 16 February 2005. The Kyoto Protocol is signed by 128 nations, and commits the participating industrialized countries to cut emissions of greenhouse gases by over 5% below 1990 levels by the period 2008-2012.

In addition to addressing the root causes of climate change, it is also important to take action to adapt to a changing climate. This includes actions that immediately improve the health of the poorest communities and also to reduce their vulnerability to climate change effects in the future.


Oceans darken

Climate change will increase precipitation in some regions of the world, resulting in stronger-flowing rivers. Stronger river currents stir up more silt and debris, which all eventually flows into the ocean and makes the ocean more opaque. Regions along the coast of Norway have already experienced increasingly darker and murkier ocean water with increased precipitation and snow melt in recent decades. Some researchers have speculated that the murkiness is responsible for changes in regional ecosystems, including a spike in jellyfish populations.


A review of the combined effects of climate change and other local human stressors on the marine environment

Climate change (CC) is a key, global driver of change of marine ecosystems. At local and regional scales, other local human stressors (LS) can interact with CC and modify its effects on marine ecosystems. Understanding the response of the marine environment to the combined effects of CC and LS is crucial to inform marine ecosystem-based management and planning, yet our knowledge of the potential effects of such interactions is fragmented. At a global scale, we explored how cumulative effect assessments (CEAs) have addressed CC in the marine realm and discuss progress and shortcomings of current approaches. For this we conducted a systematic review on how CEAs investigated at different levels of biological organization ecological responses, functional aspects, and the combined effect of CC and HS. Globally, the effects of 52 LS and of 27 CC-related stressors on the marine environment have been studied in combination, such as industrial fisheries with change in temperature, or sea level rise with artisanal fisheries, marine litter, change in sediment load and introduced alien species. CC generally intensified the effects of LS at species level. At trophic groups and ecosystem levels, the effects of CC either intensified or mitigated the effects of other HS depending on the trophic groups or the environmental conditions involved, thus suggesting that the combined effects of CC and LS are context-dependent and vary among and within ecosystems. Our results highlight that large-scale assessments on the spatial interaction and combined effects of CC and LS remain limited. More importantly, our results strengthen the urgent need of CEAs to capture local-scale effects of stressors that can exacerbate climate-induced changes. Ultimately, this will allow identifying management measures that aid counteracting CC effects at relevant scales.

Keywords: Adaptation and mitigation to climate change Cumulative effect assessment Ecosystem-based management Multiple stressors Spatially explicit assessment Systematic review.

Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.


Watch the video: Causes and Effects of Climate Change. National Geographic (May 2022).


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