Science News

October 7, 2020 | Bringing the chill of the cosmos to a warming planet https://www.washingtonpost.com/climate-solutions/2020/10/07/radiative-cooling-climate-change/?arc404=true (credit: Sarah Kaplan)

Notable Excerpts:

  • “The world now cools off with the help of more than 3.5 billion refrigerators and air conditioners, a number that is quickly growing. But those appliances are also a major source of greenhouse gas emissions. In seeking relief from the heat, humans are making the globe even hotter, compounding the demand for cooling. To break that cycle, University of California at Los Angeles materials scientist Aaswath Raman wants to turn ancient technology into a 21st-century tool. Working with colleagues, he has developed a thin, mirror-like film engineered to maximize radiative cooling on a molecular level. The film sends heat into space while absorbing almost no radiation, lowering the temperature of objects by more than 10 degrees, even in the midday sun.”
  • “It had to be cheap, so it would be accessible to people of all income levels. It had to be able to integrate into existing air-conditioning systems. As they continued to tinker with the technology, Raman and his collaborators set up a company, SkyCool Systems, to help bring it into the world.”
  • It wasn’t difficult to convince Jesus Valenzuela, store manager at the Stockton, Calif., Grocery Outlet, to test the technology. Between the deli case, the dairy aisle, the freezer section and all the backroom storage, cooling alone cost him more than $100,000 a year. […] ‘There’s a lot of technical things I don’t know about,’ he said. But that didn’t matter: The SkyCool panels had lowered his electric bill by about $3,000 over the course of the summer, he said.”

October 5, 2020 | Right-wing ideology reduces the effects of education on climate change beliefs in more developed countries https://doi.org/10.1038/s41558-020-00930-6 (credit: Gabriela Czarnek, Małgorzata Kossowska and Paulina Szwed)

Abstract: The effects of education on people’s climate change beliefs vary as a function of political ideology: for those on the political left, education is related to pro-climate change beliefs, whereas for those on the political right, these effects are weak or negative. This phenomenon has been examined mainly in the US, where climate change has become a highly politicized issue; however, climate change is less politicized in other contexts. Here we analyse the effects of education and political ideology across 64 countries and show that education has positive effects on pro-climate change beliefs at low and mid-levels of development. At higher levels of development, right-wing ideology attenuates (but does not reverse) the positive effects of education. These analyses extend previous findings by systematically investigating the between-country variation in the relationship between education, ideology and climate change beliefs. The current findings suggest that US-centric theories on the topic should not be generally applied to other contexts uncritically.

Notable Excerpts:

  • “Surprisingly, neither education nor scientific literacy has been shown to have major effects on these beliefs. Importantly, previous research, conducted mainly in the US, has demonstrated that the effects of education on climate change beliefs vary as a function of political ideology: for the political left, education has positive effects, that is, it is related to more pro-climate change beliefs, whereas for the political right, education usually has weak or negative effects”
  • “Interestingly, it has also been shown that climate change becomes more of a politicized issue in countries that rely more heavily on fossil fuels (as measured by per-capita carbon emissions) and the ideological divide over climate change is larger in these particular countries. It has been suggested that per-capita carbon emissions reflects vested interests as individuals and industries have greater incentives to engage in ideological campaigns around climate change when behavioural adjustment away from a reliance on fossil fuels would be very costly.”
  • “Using three large international datasets, we found that a citizen’s level of education is an important factor impinging on pro-climate change beliefs: people who are educated tend to be more aware that climate change is occurring and that it is due to human activity, perceiving it to be more serious and showing more support towards relevant policies. These positive effects of education have been observed especially at mid- and lower levels of a country’s development. At high levels of a country’s development, the positive effects of education become attenuated by right-wing ideology. The moderating effects of left–right identification on the belief that climate change is taking place were rather modest, whereas the most pronounced interactive effects were found for the support for climate change policy. This confirms previous findings indicating that when it comes to issues such as climate change, what is most divisive is not the characterization of the problem itself but the proposed solutions associated with the problem.”

September 28, 2020 | Divergent forest sensitivity to repeated extreme droughts https://doi.org/10.1038/s41558-020-00919-1 (credit: W. R. L. Anderegg et. al.)

Abstract: Climate change-driven increases in drought frequency and severity could compromise forest ecosystems and the terrestrial carbon sink. While the impacts of single droughts on forests have been widely studied, understanding whether forests acclimate to or become more vulnerable to sequential droughts remains largely unknown and is crucial for predict-ing future forest health. We combine cross-biome datasets of tree growth, tree mortality and ecosystem water content to quantify the effects of multiple droughts at a range of scales from individual trees to the globe from 1900 to 2018. We find that subsequent droughts generally have a more deleterious impact than initial droughts, but this effect differs enormously by clade and ecosystem, with gymnosperms and conifer-dominated ecosystems more often exhibiting increased vulnerability to multiple droughts. The differential impacts of multiple droughts across clades and biomes indicate that drought frequency changes may have fundamentally different ecological and carbon-cycle consequences across ecosystems.

Notable Excerpts:

  • “Ecosystem resilience to extreme droughts is an integrated combination of (1) the capacity of the ecosystem to persist and maintain its state and function during the disturbance, often called ‘sensitivity’ or ‘resistance’, and (2) the recovery trajectory following the disturbance. Multiple resilience-increasing and resilience-decreasing mechanisms exist at both organism (for example, tree) and ecosystem scales. The net impact of repeated droughts on Earth’s forests will depend on their balance.”
  • “At biome scales, temperate conifer forests and wet tropical forests showed the largest drought-severity-normalized increase in sensitivity in the second drought (P< 0.001 for both). The decrease in drought sensitivity in boreal forests and Mediterranean-type woodlands is intriguing and may be due to community turnover favouring more-drought-tolerant species. The Amazonian rainforest stands out as a region of increased sensitivity, which is highly relevant because the Amazon experienced two very severe droughts in 2005 and 2010, which had widely documented effects on growth, mortality and carbon cycling in the region. Given the importance of the Amazon in the global carbon cycle, and that climate projections indicate increased vapour pressure deficit (atmospheric dryness) and in some cases rainfall reductions in this region, increased sensitivity to repeated droughts is of critical concern

September 28, 2020 | Electrification of light-duty vehicle fleet alone will not meet mitigation targets https://doi.org/10.1038/s41558-020-00921-7 (credit: Alexandre Milovanoff, I. Daniel Posen and Heather L. MacLean)

Abstract: Climate change mitigation strategies are often technology-oriented, and electric vehicles (EVs) are a good example of some-thing believed to be a silver bullet. Here we show that current US policies are insufficient to remain within a sectoral CO2 emission budget for light-duty vehicles, consistent with preventing more than 2 °C global warming, creating a mitigation gap of up to 19 GtCO2 (28% of the projected 2015–2050 light-duty vehicle fleet emissions). Closing the mitigation gap solely with EVs would require more than 350 million on-road EVs (90% of the fleet), half of national electricity demand and excessive amounts of critical materials to be deployed in 2050. Improving average fuel consumption of conventional vehicles, with stringent standards and weight control, would reduce the requirement for alternative technologies, but is unlikely to fully bridge the mitigation gap. There is therefore a need for a wide range of policies that include measures to reduce vehicle ownership and usage.

Notable Excerpts:

  • “We show that betting solely on EVs to remain within suitable sectoral CO2 emission budgets for the US LDV fleet would imply more than 350 million on-road EVs in 2050, adding half of national electricity demand and requiring an excessive amount of critical materials.”
  • “In our simulations, we find that stabilizing LDV travel demand at current levels would allow the EV30@30 campaign electrification target to remain within a suitable budget, and reductions in travel demand are needed for lower electrification targets. Therefore, measures to reduce vehicle ownership and usage are critical. Such findings are in line with the idea that no single mitigation solution is sufficient, as developed by the stabilization wedges of Pacala and Socolow, and with the call for the globally reduced use of LDVs.”

September 28, 2020 | Increasing ocean stratification over the past half-century https://doi.org/10.1038/s41558-020-00918-2 (credit: Guancheng Li et. al.)

Abstract: Seawater generally forms stratified layers with lighter waters near the surface and denser waters at greater depth. This stable configuration acts as a barrier to water mixing that impacts the efficiency of vertical exchanges of heat, carbon, oxygen and other constituents. Previous quantification of stratification change has been limited to simple differencing of surface and 200-m depth changes and has neglected the spatial complexity of ocean density change. Here, we quantify changes in ocean stratification down to depths of 2,000 m using the squared buoyancy frequency N2 and newly available ocean temperature/salinity observations. We find that stratification globally has increased by a substantial 5.3% [5.0%, 5.8%] in recent decades (1960–2018) (the confidence interval is 5–95%); a rate of 0.90% per decade. Most of the increase (~71%) occurred in the upper 200 m of the ocean and resulted largely (>90%) from temperature changes, although salinity changes play an important role locally.

Notable Excerpts:

  • “Ocean stratification is quantified by density change with depth, which in turn, is determined by the vertical distribution of temperature and salinity, in addition to pressure. […] As human-caused greenhouse warming has fundamentally altered oceanic temperature and salinity fields, impacts to stratification are expected. An increase in near-surface stratification during the second half of the twentieth century has been documented, but characterization of the temporal and spatial changes in stratification have been controversial.”
  • “Increasing stratification has important climate implications. The expected decrease in ocean ventilation could affect ocean heat and carbon uptake, water mass formation and tropical storm formation and strength. The associated decrease in ocean mixing, more-over, is consistent with a decline in ocean oxygen concentration, reduced nutrient flux and alteration of marine productivity and biodiversity, as observed. Projected future changes in stratification, also have implications for density-driven ocean circulation changes and, in particular, the Atlantic Meridional Overturning Circulation, which already shows some evidence of slowdown.”

September 25, 2020 | Phytoplankton dynamics in a changing Arctic Ocean https://doi.org/10.1038/s41558-020-0905-y (credit: Mathieu Ardyna and Kevin Robert Arrigo)

Abstract: Changes in the Arctic atmosphere, cryosphere and Ocean are drastically altering the dynamics of phytoplankton, the base of marine ecosystems. This Review addresses four major complementary questions of ongoing Arctic Ocean changes and associated impacts on phytoplankton productivity, phenology and assemblage composition. We highlight trends in primary production over the last two decades while considering how multiple environmental drivers shape Arctic biogeography. Further, we consider changes to Arctic phenology by borealization and hidden under-ice blooms, and how the diversity of phytoplankton assemblages might evolve in a novel Arctic ‘biogeochemical landscape’. It is critical to understand these aspects of changing Arctic phytoplankton dynamics as they exert pressure on marine Arctic ecosystems in addition to direct effects from rapid environmental changes.

Notable Excerpts:

  • “The reduction in sea-ice extent in the Arctic Ocean over the last few decades has resulted in both a longer phytoplankton growing season and increased open-water habitat for phytoplankton growth. Consequently, phytoplankton blooms now begin earlier and end later in the year, and annual net primary production (NPP) in open waters over the entire Arctic Ocean increased 30% between 1998 and 2012, the year that summer sea-ice extent reached its historical minimum.”
  • “Overall, Arctic and sub-arctic phytoplankton communities seem to be relatively resilient to ocean acidification, with no significant change in productivity and little change in species assemblages under enriched scenarios up to 1,000 μatm pCO2. Contrasting responses between species, however, seem to be characteristic of more acidic subarctic and Arctic waters. For example, small picoeukaryotes seem to benefit from higher pCO2, while prymnesiophytes (including coccolithophores) are generally negatively impacted, and vary-ing responses are noted in diatoms.”
  • “More importantly, the increasing long-term influx of freshwater into northeastern subarctic Atlantic surface waters may be implicated in driving the industrial-era Atlantic Meridional Overturning Circulation (AMOC) decline and contributed to this primary productivity decline over the late nineteenth and twentieth centuries. Continued weakening of the AMOC, as projected for the twenty-first century, may therefore result in further productivity declines, with important ramifications for future atmospheric C drawdown and northern Atlantic fisheries in the subarctic Atlantic Ocean.”

September 15, 2020 | New Climate Maps Show a Transformed United States https://projects.propublica.org/climate-migration/?fbclid=IwAR0Se9WG6lc6hogwB6n6UFT66njF3usd54LB9V7se8pP5yscD21JXDJ36mU (credit: Al Shaw, Abrahm Lustgarten)

Notable Excerpts:

  • “According to new data from the Rhodium Group analyzed by ProPublica and The New York Times Magazine, warming temperatures and changing rainfall will drive agriculture and temperate climates northward, while sea level rise will consume coastlines and dangerous levels of humidity will swamp the Mississippi River valley.”
  • “By midcentury, heat and humidity in Missouri A will feel like Louisiana does today, while some areas we don’t usually think of as humid, like southwestern Arizona B, will see soaring wet bulb temperatures because of factors like sun angle, wind speed and cloud cover reacting to high temperatures, according to Hannah Hess of the Rhodium Group.”
  • “With heat and evermore prevalent drought, the likelihood that very large wildfires (ones that burn over 12,000 acres) will affect U.S. regions increases substantially, particularly in the West, Northwest and the Rocky Mountains, but also in Florida, Georgia and the Southeast, according to peer-reviewed research published in the International Journal of Wildland Fire.”
  • “Taken together, some parts of the U.S. will see a number of issues stack on top of one another — heat and humidity may make it harder to work outside, while the ocean continues to claim more coastal land.”

September 7, 2020 | Wrong-way migrations of benthic species driven by ocean warming and larval transport https://doi.org/10.1038/s41558-020-0894-x (credit: Heidi Fuchs, et. al. 2020)

Abstract: Ocean warming has predictably driven some marine species to migrate polewards or to deeper water, matching rates of environmental temperature change (climate velocity) to remain at tolerable temperatures. Most species conforming to expectations are fish and other strong swimmers that can respond to temperature change by migrating as adults. On the Northwest Atlantic continental shelf, however, many benthic invertebrates’ ranges have instead shifted southwards and into shallower, warmer water. We tested whether these ‘wrong-way’ migrations could arise from warming-induced changes in the timing of spawning (phenology) and transport of drifting larvae. The results showed that larvae spawned earlier in the year encounter more downwelling-favourable winds and river discharge that drive transport onshore and southwards. Phenology and transport explained most observed range shifts, whereas climate velocity was a poor predictor. This study reveals a physical mechanism that counterintuitively pushes benthic species, including commercial shellfish, into warmer regions with higher mortality.

Notable Excerpts:

  • “Ocean warming has predictably driven some marine species to migrate polewards or to deeper water, matching rates of environmental temperature change (climate velocity) to remain at tolerable temperatures.  The paradigm that species’ ranges are controlled by thermal tolerance is intuitive but fails to explain ranges shifting unexpectedly towards warmer temperatures.”
  • “Despite being highly dispersive, benthic species may be unable to follow climate velocities when the physics-driven transport of larvae opposes temperature-driven shifts of adult ranges. Changes in planktonic transport have far-reaching consequences for community structure and biogeography but are among the least understood impacts of warming on marine systems”
  • “As climate change reduces yields from traditional fisheries, the seafood industry may rely more heavily on invertebrates, including shellfish, that disperse as larvae. Of the commercial species included here, scallops (Placopecten magellanicus) spawn at a wide range of temperatures, and their ranges have remained relatively constant. In contrast, clams (Arctica islandica and Spisula solidissima) and mussels (Mytilus edulis) spawn primarily at low temperatures, and their ranges have warmed and contracted.”

August 17, 2020 | Increasing threat of coastal groundwater hazards
from sea-level rise in California https://doi.org/10.1038/s41558-020-0874-1 (credit: K. M. Befus, et. al. 2020)

Abstract: Projected sea-level rise will raise coastal water tables, resulting in groundwater hazards that threaten shallow infrastructure and coastal ecosystem resilience. Here we model a range of sea-level rise scenarios to assess the responses of water tables across the diverse topography and climates of the California coast. With 1 m of sea-level rise, areas flooded from below are predicted to expand ~50–130 m inland, and low-lying coastal communities such as those around San Francisco Bay are most at risk. Coastal topography is a controlling factor; long-term rising water tables will intercept low-elevation drainage features, allowing for groundwater discharge that damps the extent of shoaling in ~70% (68.9–82.2%) of California’s coastal water tables. Ignoring these topography-limited responses increases flooded-area forecasts by ~20% and substantially underestimates saltwater intrusion. All scenarios estimate that areas with shallow coastal water tables will shrink as they are inundated by overland flooding or are topographically limited from rising inland.

Notable Excerpts:

  • Over the next century, rising sea levels are predicted to cause widespread inundation of coastal terrestrial areas, wetland loss and more severe nuisance flooding. Relative sea levels are projected to increase for much of Earth’s coastline, presenting a wide range of coastal hazards for the ~1 billion people living in low-elevation coastal areas by 2050. Along with the increasing exposure of coastal communities to overland flood risk, rising sea levels will cause unconfined coastal groundwater levels (that is, water tables) to rise, leading to inland flooding hazards via subsurface connections to the sea.
  • Compared with the impacts of direct marine inundation, the responses of groundwater to sea-level rise may lead to earlier, more severe or longer-term hazards to terrestrial water resources, ecosystems and infrastructure and could contribute substantially to the projected hundreds of millions of people displaced by climate change over the next century.