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 May 2019. (To get these updates delivered right to your inbox, sign up for our Hot Science newsletter.)


  • Climate change may affect fertility: Using a model examining economic impacts of climate change, scientists found that climate change may affect fertility. In regions where climate decreases crop yields, parents spend fewer resources in the education of their children and have more babies. The opposite is true in higher latitudes, where fertility decreases and education increases.
  • Species on the brink of extinction: In an alarming landmark report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, scientists reported that the rate of species extinction is accelerating and the health of ecosystems is deteriorating quickly. Climate change is the third-leading factor in the driver of change, following land and sea use changes and direct exploitation, such as resource extraction.
  • Mass puffin die-off: Scientists reported an unusual level of mortality of Tufted puffins in Alaska’s eastern Bering Sea from October 2016 though January 2017. Evidence showed that more than 350 puffins died, likely from starvation. The authors suggested that changes in prey abundance and/or distribution played a role in the mass die-off. The article noted that mass mortality events have been linked to warmer temperatures.
  • Threats to Australia’s endemic speciesModelers studying future climate impacts in Australia’s Great Dividing Range found that 26 vertebrate species, including 11 endemic species found nowhere else on Earth, will have no suitable habitat in 2085 under a high emissions scenario.
  • Climate impacts to food already evidentScientists found that climate change has already affected critical crop species, including a 1% decline in consumable food calories across 10 crops due to yield losses. Europe, Southern Africa and Australia experienced the biggest declines, while climate changes interestingly had a positive effect in Latin America. In another article, researchers found that 20-49% of yield anomalies of maize, soybeans, rice and spring wheat from 1961-2008 can be attributed to climatic factors like temperature extremes.
  • Lakes drying up in Greenland: Analyzing small lakes in Greenland, scientists  found that smaller ponds declined by 28% in number and 15% in area between 1969 and 2017. Accordingly, parts of Greenland are becoming drier, increasing the risk of tundra fires.
  • Climate impacts to whales: Whales in the Gulf of Maine are altering their foraging behavior due to changing ocean currents. Researchers found that whales are increasingly struck by ships and entangled in fishing gear as they deviate from their typical migration patterns.
  • Every degree of warming matters: The world has already experienced 1 degree C of warming; with an additional degree of warming, researchers  found that remaining species and suitable habitat will decline by 14% and 35%, respectively.
  • Non-native species can adapt betterScientists exposed native and non-native plants to warming and found that non-native species flowered earlier than native species. This advantage can allow non-native species to spread geographically.
  • Dying frogs: Warming may lead to severe outbreaks of ranavirus, resulting in higher mortality rates for frogs.
  • Rotten bananas: Researchers  found that Black Sigatoka, a banana disease, has increased in Latin America and the Caribbean since the 1960s. Scientists blame wetter conditions and temperature changes.
  • Species to get smaller: A study posited that small, fertile, faster, insect-eating generalists will fare better in a changing climate, leading to changes in species composition.
  • No adapting to acidic waters: Scientists tested the ability of coral and calcifying macroalgal species to acclimatize to ocean acidification. They found that none could do so, underscoring the threat ocean acidification poses to reefs.


  • Ocean waves get bigger: Scientists used global satellite data to assess trends in the ocean’s wind speed and wave height from 1985 to 2018. They found a small increase in average wind speed and a significant gain in wave height, with the largest changes in the Southern Ocean. Both wind speed and wave size have important implications for sea level rise.
  • Human-induced warming caused Japanese heat wave: Scientists found that the July 2018 record-breaking heat in Japan would “never have happened” without human-induced warming. They also predicted that with 2 degrees C of warming, extreme hot days will increase by 1.8 times.
  • Weaker Asian monsoon: Scientists found that aerosol emissions are a major cause of an unprecedented weakening of the  Asian summer monsoon from 1934-2013. Weak Asian summer monsoons can lead to droughts and locust plagues.
  • Extreme heat for northeastern US: What used to be a one-day-per-year extreme heat event will hit the most vulnerable communities in the rural northeastern United States 23 times per year by 2046-2075, under a high emissions scenario.
  • Human influence on drought: Assessing human influence on global drought has been challenging given lack of records and significant natural variability. In a new study, scientists used data from tree rings to examine the role of human activities, including those leading to increases in greenhouse gases. They found a clear signal that human activities affected drought risk as early as the beginning of the 20th century.


  • Sea level rise estimates higher than previously thought: Scientists found that the upper estimate of global sea level rise will exceed 2 meters (6 feet) by the end of the century under a high emissions scenario. This level of sea level rise is 2 times that of the Intergovernmental Panel on Climate Change’s report. It would displace 187 million people and submerge 1.8 million square kilometers of coastline, including important food-producing regions.
  • Green oceans: Because the winter’s growing season is getting longer, the Southern Ocean is becoming greener due to increased phytoplankton over the past 21 years. The Southern Ocean plays a critical role in regulating the Earth’s climate.


  • Antarctica Ice Sheet thinning: Researchers found that between 1992 and 2017, West Antarctica’s ice thinned by almost a quarter. Altogether, ice losses from both East and West Antarctica have led to 4.6 millimeters of sea level rise.
  • Disappearing glaciers: The Glacier Model Intercomparison Project found that across 19 glacier regions (excluding Antarctica and Greenland ice sheets), mass loss of glaciers will increase 18-36% by the end of the century. This level of melt would cause seas to rise by almost 10 inches.
  • Glacier melt can counteract drought: Extreme drought has affected millions across Asia, risking migration, conflict and instability. A scientist  found that meltwater from Asia’s high-mountain glaciers is counteracting drought stress, providing a critical water source during times of water scarcity. He suggested that summer meltwater provides for the needs of 221 million people.


  • Rising CFCs in China: Scientists detected a rise in trichlorofluoromethane (CFC-11), a potent greenhouse gas,  from eastern China after 2012. They noted that the increase is likely from new, unreported production and use. An increase in CFC-11 is inconsistent with the Montreal Protocol, an international agreement to phase out global CFC production by 2010.