Every month, climate scientists make new discoveries that advance our understanding of climate change's causes and impacts. The research gives a clearer picture of the threats we already face and explores what's to come if we don't reduce emissions at a quicker pace.
Our blog series, This Month in Climate Science, offers a snapshot of the month's significant scientific literature, compiled from some of the leading peer-reviewed journals. This edition explores studies published in February 2019. (To get these updates delivered right to your inbox, sign up for our Hot Science newsletter.)
Impacts to Ecosystems and Infrastructure
- First mammal goes extinct from climate change: The Australian government announced that the Bramble Cay melomys is now extinct. Three years ago, scientists warned that the rodent species had likely gone extinct due to ocean inundation in the low-lying cay where it lived. This is the first documented mammal to go extinct due to climate change.
- Warming seas strand sea turtles: Thanks to rising sea surface temperatures in the U.S. Gulf of Maine, Kemp’s ridley sea turtle populations are expanding northward into areas like Cape Cod Bay. Once they’re there, they sometimes encounter colder water that stuns them into lethargy. Presenting further challenges, Cape Cod Bay’s hook shape can act as a catchment for turtles trying to migrate South in the colder months.
- Climate change drives insect extinction: A review study found that more than 40 percent of insect species are threatened with extinction over the next few decades, thanks to climate change, habitat loss, pesticide and fertilizer use, and biological factors such as introduced species. Climate change poses the largest threat in the tropics. Because insects are at the base of many of the world’s ecosystems, the impacts of their extinction could be catastrophic.
- Implementation of Paris Agreement protects fisheries: Researchers found that meeting the goals of the Paris Agreement (limiting global temperature rise to 1.5-2 degrees C (2.7-3.6 degrees F)) would preserve millions of metric tons of fish catch and billions of dollars of income each year. Three-quarters of maritime countries would reap such benefits, with 90 percent of the protected catch occurring in waters of developing countries, whose populations are more dependent on seafood for protein.
- Fish yields decline: A study found that yields of 124 fish species declined by 4 percent from 1930 to 2010, with five ecoregions witnessing losses on the order of 15-35 percent. While some species faired well in warm waters, the large majority experienced a decline.
- Birds on the move: A study examining almost 200 bird species from 1959-2015 found that as temperatures rose, spring migration advanced a week earlier and migration season length increased. The timing of species migration can affect broader ecosystems by altering predator-prey relationships.
- Tigers lose habitat from sea level rise: Researchers modeled the impacts of rising seas on the endangered Bengal tiger in the Bangladesh Sundarbans, a low-lying mangrove ecosystem. They found that as a result of climate change and sea level rise, there will be no suitable Bengal tiger habitat left by 2070.
- Floods threaten dams: Scientists assessed the risk that climate change poses to California’s major dams, finding that most are at risk of failure from flooding. Dam failure can lead to a decrease in water storage, evacuations, and even greater catastrophes, such as fatalities, if the dams’ structural integrity weakens.
- Rate of intensification of Atlantic hurricanes increases: Scientists found that hurricanes in the Atlantic basin intensified between 1982 and 2009. The intensification is outside the range of normal climate variability, and authors concluded that human-induced warming is likely to blame.
- Temperature extremes get less noteworthy: Studying social media posts about weather, scientists found that as people are exposed to repeated temperature extremes, their reference point for what is normal shifts. Accordingly, people may fail to notice the impacts of climate change as they become less remarkable to them.
- Extreme weather causes billion-dollar losses: The U.S. National Oceanic and Atmospheric Administration found that 14 weather and climate disasters in the United States led to damages of at least $1 billion each in 2018. The disasters, which included Hurricanes Michael and Florence and Western wildfires, cost $91 billion and killed 250 people.
- Floods ruin foot traffic: Studying Annapolis, Maryland, scientists found that high-tide floods reduced visits to the downtown area by 2 percent in 2018. With an additional foot of sea level rise, visits to the city are projected to drop 24 percent.
Emissions and Temperatures
- U.S. methane emissions grow: The U.S. Environmental Protection Agency released a draft inventory showing that methane emissions grew in 2017.
- More methane from thawing permafrost: A study found that a warmer, wetter climate can increase methane emissions from permafrost by about 30 percent. Microbial and plant processes are starting earlier in the growing season, leading to greater emissions. Methane has a warming effect 28 times that of carbon dioxide.
- Disintegrating clouds: Scientists found that stratocumulus clouds, which play an important role in climate regulation by reflecting solar radiation back into space, would break apart under very high levels of carbon dioxide (above 1200 parts per million, or 3 times today’s levels). The authors suggest the world would see an 8˚C (14.4 ˚F) increase in warming under this scenario.
- Growing source of black carbon: “Black carbon,” a potent climate forcer, is a growing concern due to increased air traffic, which is expected to double in the next two decades. A recent study found that black carbon emissions from aviation are roughly equivalent to 11 percent of North America’s road emissions.
- Diseases contributed to the “Little Ice Age”: Researchers have now uncovered a surprising chain of events that led to a decline of atmospheric concentrations of carbon dioxide in the late 1500s/early 1600s. After the Europeans arrived in the Americas, the epidemics they brought with them killed about 90 percent of indigenous populations over the next century. The resultant abandonment of land and forest regrowth increased carbon sequestration.
- A carbon-storage breakthrough: A new study describes a novel approach of using liquid metal electrolysis to sequester carbon dioxide and turn it into solid carbon. An added benefit is that the new solid can hold an electric charge, becoming a supercapacitator that can be used in vehicles. The authors describe it as a critical first step in advancing carbon storage.
- “Gold standard” level of confidence that humans are causing climate change: Researchers examined when the first human-induced warming signal emerged in the scientific data. They found that there is about a one in 3.5 million chance we would see the temperature increases we are seeing today in the absence of human activities. This level of scientific confidence is considered the “gold standard” for discoveries in particle physics.
- Color-changing oceans: Researchers found that in some areas, such as the Caribbean, phytoplankton populations will decline in a changing climate, making the oceans bluer. In other regions, such as the Southern Ocean and North Atlantic, warming waters will foster faster-growing phytoplankton, making the waters look greener. Monitoring of such color changes can be a helpful indicator of climatic changes.
- More flooding in low-elevation zones than previously thought: Examining coastal Louisiana, the largest low-elevation coastal zone in the United States, one study found that tide gauges and satellites underestimate rates of sea level rise. Low-elevation coastal zones may therefore be at a higher risk of flooding than previously assumed.
- Himalayan glaciers at risk: A new study of the Hindu Kush Himalaya Region, conducted as part of a broader assessment, projects that glacier volumes will decline by up to 90 percent by 2100. More than 1.3 billion people depend on river water from the Himalayan glaciers.
- Overestimated sea level rise projections: Many sea level rise projections are informed by a hypothesis related to marine ice-cliff instability, which anticipates ice cliff collapse after the disintegration of ice shelves. A new study suggests that projections made with marine ice-cliff instability overestimate sea level rise, and modelers should revise their estimates downward.
- New glacier ice estimates: A study estimates ice thickness for all 215,000 glaciers outside of the Greenland and Antarctic ice sheets. Scientists found a total of 158 cubic kilometers of ice, which, if fully melted, would lead to 0.3 meters of sea level rise, which may inform future sea level rise projections. They also determined that Asia’s high-mountain glaciers hold about 27 percent less ice than earlier estimates suggest, and that the region could lose half of its current glacier area a decade earlier than previously estimated.
- Arctic ice loss may speed up soon: Arctic ice loss is affected by human-induced warming and natural climate variability. One natural cycle, called the Interdecadal Pacific Oscillation (IPO), can change atmospheric wind patterns, affecting heat transport to the Arctic. Scientists now believe that the IPO is shifting into a phase which will increase the odds of accelerated sea ice loss in the next few decades.
- Now ice-free Canadian Arctic had been ice-covered: Scientists found that locations in the Canadian Arctic that are currently ice-free had previously been continuously covered by ice for more than 40,000 years. Also, the summer warmth of the past century exceeds anything in the last 115,000 years.
- Climate change creates new economic opportunities for Greenland: As the Greenland ice sheet shifts and melts, a new study found that sand and gravel will accumulate at the country’s coasts. This could create an economic opportunity for Greenland, as sand and gravel reserves are depleting globally from rising demand.
EDITOR'S NOTE, 3/20/19: A previous version of this blog post stated that Atlantic hurricanes are getting stronger. It is actually their rate of intensification that has increased, likely due to human-induced warming. We have updated the text to correct the error.