Center for Climate Sciences

The Arctic region is heating up twice as fast as the global average. Despite relatively few plant per area compared to the temperate and tropic regions, Arctic regions are key stores of soil organic carbon (SOC) which play a major role in the greenhouse gas balance of high-latitude ecosystems. Read more >

The Arctic region is heating up twice as fast as the global average. Despite relatively few plant per area compared to the temperate and tropic regions, Arctic regions are key stores of soil organic carbon (SOC) which play a major role in the greenhouse gas balance of high-latitude ecosystems. Cold and sometimes moist environment conditions slow down the dead plant matter decomposition. This process emits the two most powerful greenhouse gases, methane (CH₄) and carbon dioxide (CO₂). While CH₄ emission accounts for a smaller component of the C balance, the climatic impact of CH₄ outweighs CO₂ (28-34 times larger Global Warming Potential on a 100-year scale), highlighting the need to jointly resolve the climatic sensitivities of CO₂ and CH₄.

Here we use a terrestrial biosphere model and field observations to understand what drives CO₂ and CH₄ exchanges in Alaska. Based on the combined CO₂ and CH₄ flux responses to climate variables, we find that 1970-present climate trends will induce positive C-climate feedback at all tundra sites (net warming effect), and negative C-climate feedback at the boreal and shrub fen sites (net cooling effect). The positive C-climate feedback at the tundra sites is predominantly driven by increased CH₄ emissions while the negative C-climate feedback at the boreal site is predominantly driven by increased CO₂ uptake (80% from slowed decomposition, and 20% from increased photosynthesis). This study demonstrates the need to jointly consider CO₂ and CH₄ biogeochemical processes – and their associated climatic sensitivities – in order to resolve the sign and magnitude of high-latitude ecosystem C-climate feedback in the coming decades.

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Heatwaves in California occur in both dry and humid forms, but recent studies indicate a shift towards more humid events. This research focuses on two contrasting heatwaves that affected southern California in the summer of 2020. Read more >

Heatwaves in California occur in both dry and humid forms, but recent studies indicate a shift towards more humid events. This research focuses on two contrasting heatwaves that affected southern California in the summer of 2020, providing an excellent opportunity to understand the impacts of humid versus dry heatwaves on the urban environment, specifically in the greater Los Angeles metropolitan region (as shown in figure 1). The results reveal that, despite the September heatwave having higher air temperatures, the humid heat stress – quantified using wet bulb temperature linked to the risk of heat stroke – was greater in August. While dry and humid heat display different spatial patterns, three distinct spatial clusters emerge based on non-heatwave local climates. Both types of heatwaves reduced the gradient of heat stress within the city, with valley areas experiencing the most significant increase in heat stress. Notably, valley regions such as San Bernardino and Riverside faced the most severe impacts, with up to a 6±0.5℃ additional heat stress during heatwave nights.

While Southern California is no stranger to extreme heat, these findings highlight the importance of including moist heat in extreme heat warning frameworks and considering the diverse impacts of heatwaves at a fine scale within urban areas. Such insights play a crucial role in designing policies that facilitate fair and effective mitigation strategies for extreme heat, ensuring equitable protection for all communities.

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As concerns about climate change continue to mount, a recent study conducted by a team of scientists at Jet Propulsion Laboratory and California Institute of Technology has shed light on the effects of climate change on the Arctic-Boreal carbon balance. Read more >

As concerns about climate change continue to mount, a recent study conducted by a team of scientists at Jet Propulsion Laboratory and California Institute of Technology has shed light on the effects of climate change on the Arctic-Boreal carbon balance. In recent history, some of the excess carbon dioxide we produce is taken up by forests (called a “carbon sink”), but there is concern that this benefit may not continue as the climate changes. This study used two groups of Earth system models to predict the future of vegetation for the North American Arctic-Boreal region.

Both model group ensembles suggested a tipping point in the Net Biome Production (NBP) curve, indicating that the Arctic-Boreal ecosystems may become less productive by 2050-2080 and will stop absorbing excess carbon dioxide in the next century. This information is significant for policymakers as it highlights the urgent need for climate change mitigation and adaptation strategies to address the potential shift in the carbon balance of this vulnerable region. Further research and action are required to better understand and mitigate the impacts of climate change in the Arctic-Boreal region and protect this critical carbon sink.

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Land surface models are vital for predicting how our planet will respond to climate change. By combining these models with satellite-based observations – historically and in real time – we can make more accurate predictions. Read more >

Land surface models are vital for predicting how our planet will respond to climate change. By combining these models with satellite-based observations – historically and in real time – we can make more accurate predictions. Scientists at the Jet Propulsion Laboratory and California Institute of Technology have developed the Climate Modeling Alliance (CliMA) Earth System Model, representing a significant advancement in climate prediction. By successfully integrating satellite data, CliMA Land predicts the behavior of carbon and water, as well as vegetation response.

This advancement has the potential to enhance our understanding of global vegetation dynamics and contribute to more accurate climate and ecosystem models, aiding in the development of effective strategies for mitigating and adapting to climate change impacts. CliMA Land represents a promising revolution in land surface modeling, leveraging remote sensing data to improve predictions and advance our understanding of the Earth's ecosystems.

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In the quest to better understand Earth's ecosystems, scientists at Jet Propulsion Laboratory, California Institute of Technology and Oak Ridge National Laboratory, leveraging remote sensing data and Earth system modeling, have made significant strides in uncovering the global carbon costs associated with plant nutrient acquisition. Read more >

In the quest to better understand Earth's ecosystems, scientists at Jet Propulsion Laboratory, California Institute of Technology and Oak Ridge National Laboratory, leveraging remote sensing data and Earth system modeling, have made significant strides in uncovering the global carbon costs associated with plant nutrient acquisition. Plants rely on nutrients in the soil to grow, including Nitrogen (for leaf growth) and Phosphorus (for root development and growing seeds, flowers, and fruit). However, declining levels of these nutrients are detrimental to plant health. This study used cutting-edge models to understand global plant nitrogen and phosphorus uptake. The results revealed that both nutrients co-limit 80% of the global land area, with plants investing a substantial amount of energy to acquire these nutrients from multiple uptake pathways, including symbiotic relationships with fungi - mycorrhiza.

The study's findings have significant implications for our understanding of land productivity worldwide and climate change predictions. By considering the carbon costs of nutrient acquisition, the model and observations agreement increased, reducing uncertainty in predictions. The use of remote sensing data in this study has enabled a more comprehensive and accurate representation of plant nutrient acquisition in Earth system models, paving the way for improved modeling and better insights into the global carbon cycle. This research highlights the importance of leveraging remote sensing techniques to gain valuable insights into complex Earth system processes and improve our understanding of global biogeochemical cycles.

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In early 2020, as the COVID-19 pandemic spread around the globe, many countries imposed strict lockdowns to slow the spread of the coronavirus. As people stayed home, ground and air travel decreased, allowing us to study the impact on air pollution.

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In early 2020, as the COVID-19 pandemic spread around the globe, many countries imposed strict lockdowns to slow the spread of the coronavirus. As people stayed home, ground and air travel decreased, allowing us to study the impact on air pollution. Scientists at the NASA Jet Propulsion Laboratory (JPL), the Royal Netherlands Meteorological Institute (KNMI), the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), and Nagoya University have collaborated to estimate the detailed changes in emissions and ozone across the world.

Of particular interest are global emissions of nitrogen oxides (NOx), which create ozone and are a danger to human health as well as a driver of climate change. The global COVID-19 lockdowns resulted in a decrease in NOx by 15% globally, with local reductions as high as 50%. This resulted in a 2% reduction of ozone in the troposphere (the lower portion of the atmosphere) by June 2020. The Intergovernmental Panel on Climate Change (IPCC), the authoritative body of international experts on climate, have proposed significant NOx emission controls to reduce global warming, but even the most aggressive of these were expected to decrease NOx by 4% over a 30-year period. The COVID-19 lockdowns temporarily achieved half of that target in just a few months.

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The influenza, or flu, virus infects millions of people in the United States each year, mostly during winter. To help limit the impacts of seasonal flu outbreaks, scientists have been trying to anticipate when the outbreaks occur using a variety of information.

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The influenza, or flu, virus infects millions of people in the United States each year, mostly during winter. To help limit the impacts of seasonal flu outbreaks, scientists have been trying to anticipate when the outbreaks occur using a variety of information. Laboratory studies have pointed to humidity playing an important role in the transmission of flu. The average amount of water vapor in the air we breathe varies widely across the U.S., but even in the most humid areas, it begins to drop as winter approaches.

Researchers at NASA’s Jet Propulsion Laboratory and the University of Southern California have used NASA satellite data from the Atmospheric Infrared Sounder (AIRS) to illuminate the relationship between low humidity and the outbreak of flu in the U.S. They compared AIRS measurements of water vapor in the lower atmosphere with flu case estimates over a twelve year period. For each state, they identified specific levels of low humidity that signal the start of a flu outbreak. These threshold levels of low humidity vary between the states but follow regional patterns and are tied to each state’s average climate. States with humid climates, such as those in the Southeast, have higher threshold values than arid states, including those in the West and Southwest.

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When designing a space mission, there are many parameters to take into account. There are often trade-offs between different design parameters.

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When designing a space mission, there are many parameters to take into account. For instance, a space-borne instrument will observe a swath of the Earth’s surface as it orbits, and the width of that swath depends on the instrument itself, as well as high above the Earth it flies. There are also often trade-offs between different design parameters. For example, the same instrument can be used in a mission that acquires very fine features on the surface infrequently, or it can focus on larger features but visit them more often. It can be difficult to optimize these design decisions for missions that produce many products in different science focus areas (e.g. the design best for studying water is probably not the same as the design best for land).

NASA’s Earth System Observatory will include a mission to map Earth’s Surface Biology and Geology. The mission will monitor volcanic eruptions, snow-melt, water quality, vegetation health, and more. Each of these areas prioritize different instrument parameters. This study proposed a new metric by which to optimize mission design parameters: intrinsic dimensionality. This is a mathematical metric independent of application area, and can be used to design a mission that provides the best compromise between the needs of different areas.

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Heat stress is a rapidly increasing threat to human health and energy demand across the US and the globe. Both high temperatures and high moisture levels are important contributors to heat stress, and it is well-known that future temperature increases will generally be larger in mountains due to there being much less snow and drier soils.

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Heat stress is a rapidly increasing threat to human health and energy demand across the US and the globe. Both high temperatures and high moisture levels are important contributors to heat stress, and it is well-known that future temperature increases will generally be larger in mountains due to there being much less snow and drier soils. But with moisture increasing rapidly at low elevations, which factor will dominate the total response?

Scientists at JPL and several other institutions looked at all available high-resolution climate-model data and found that the temperature effect best explains the total change in heat stress. However, the more humid a climate zone, the more moisture matters in explaining the magnitude of the changes. These findings help understand where and why heat stress is likely to increase most dramatically, and motivate efforts to make investments and other preparations in the areas of greatest change, such as the southern Appalachians and southern Rocky Mountains.

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Sequences of extreme climate events, or multiple ones occurring simultaneously, can have impacts that are ‘larger than the sum of their parts’.

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Sequences of extreme climate events, or multiple ones occurring simultaneously, can have impacts that are ‘larger than the sum of their parts’. For example, bad harvests in several major crop-growing areas can lead to shortages, price shocks, and malnutrition, while oscillations between wet and dry years create larger wildfire risks than dry years alone, by increasing the quantity of vegetation available for burning. Using many versions of the same climate model to represent these events increases the confidence with which scientists can draw conclusions about them.

JPL scientists and colleagues looked at 100 end-of-century climate-model outputs for specific sets of conditions that have been linked to impacts on, for example, food security and wildfire risk. The heat-and-drought levels that historically cause bad harvests will occur simultaneously in the six major corn-growing areas about every 4 years, versus every 18 years now. The chance of a very wet year followed by a very dry year will increase by about 25% in California and many other wildfire-prone areas. Such multi-part interactions are critical to take into account for societal resilience in a warming climate.

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In the first year of the COVID-19 pandemic, measures enacted by local, state, and national governments to slow the spread of the virus also caused reductions in some human activities, such as traffic. This, in turn, led to lower emissions of greenhouse gases and air pollutants in a very short time period.

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In the first year of the COVID-19 pandemic, measures enacted by local, state, and national governments to slow the spread of the virus also caused reductions in some human activities, such as traffic. This, in turn, led to lower emissions of greenhouse gases and air pollutants in a very short time period. Changes in emissions that would normally take years or decades occurred over a few weeks, which gave a novel view into the relationship between human activities and atmospheric composition.

The Keck Institute for Space Studies launched a workshop to study these pandemic-induced changes. The results highlighted important ways climate and air quality are linked, such as reduced air pollutant emissions increasing the lifetime of methane in the atmosphere, or wildfires in the western US, which are worsening in response to climate change, causing poor air quality despite the reduction in traffic emissions. A key message was that it is becoming increasingly important to treat air quality and greenhouse gases as truly intertwined challenges.

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As our climate changes, droughts are becoming more frequent, with more than 20% of land in the Western US currently experiencing extreme or exceptional drought.

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As our climate changes, droughts are becoming more frequent, with more than 20% of land in the Western US currently experiencing extreme or exceptional drought. Monitoring these droughts is important for farmers, resource managers, and other leaders to allocate resources to the hardest-hit regions. It is also important for scientists to understand the way that different plants respond to heat and drought, in order to predict how ecosystems may behave in the future.

Scientists at the NASA Jet Propulsion Laboratory (JPL) and the United States Department of Agriculture (USDA) have collaborated to produce a data product derived from ECOSTRESS, a thermal instrument on the International Space Station (ISS). This measure of plant stress is called evapotranspiration and is now available to the general public. The remote sensing product has been shown to be highly representative of ground conditions.

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NOx is a family of air pollutants that are a key factor controlling amounts of both ozone and particulate matter (PM) in the air. Reducing NOx emissions has been an important strategy for improving air quality in the US for decades.

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NOx is a family of air pollutants that are a key factor controlling amounts of both ozone and particulate matter (PM) in the air. Reducing NOx emissions has been an important strategy for improving air quality in the US for decades. But emissions are only one half of the equation setting the amount of NOx in our cities’ air – its lifetime, or how long it stays in the air, is equally important.

Observation of NOx from space provide a unique insight into NOx lifetime. How quickly NOx concentrations decrease downwind of a source (such as a city) can be seen from space, and that rate of decrease gives a good measure of NOx lifetime. Scientists from UC Berkeley used NASA data to track how NOx lifetime changed in almost 50 cities across North America. They found that changes in lifetime help explain why NOx concentrations in the US haven’t been decreasing after 2010, despite evidence that emissions have continued to decrease.

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