Six pieces of evidence that prove climate change is real

Climate change is often treated as a political issue, but it shouldn’t be.

The facts are these: The climate of our planet is changing at a pace unlike anything seen in the natural fluctuations traced across geological records, and scientists have overwhelmingly traced this global warming trend to human activity.

Unless you’re a supercomputer, you’ll find it virtually impossible to keep an eye on every single indicator of climate change. Here are a few that scientists use to monitor the planet:

For more, check out this story on how we know climate change is happening—and that humans are causing it.

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CO2 in the atmosphere

• Measured in: parts per million (ppm)
• Where to check: Scripps Institution of Oceanography/Mauna Loa Observatory
• The latest: 405.67 ppm
• Why it matters: Carbon dioxide made up 81 percent of the United States’ greenhouse gas emissions in 2014. Fossil fuels and certain chemical reactions produce this odorless, colorless gas—a gas that traps heat in the atmosphere. Despite sinks that remove CO2 from soil, forests, and the ocean, industrial-era emissions mean that CO2 levels are the highest they have ever been in hundreds of millions of years.
• What will help: Reducing fossil fuels is the number one way to reduce atmospheric CO2. Energy efficiency, carbon capture, and market-based controls are among the most effective measures to curb carbon dioxide concentrations.
• Who rang the alarm: Thermal equilibrium of the atmosphere with a given distribution of relative humidity (Manabe and Wetherald, 1967)
• Learn more: U.S. Greenhouse Gas Inventory Report (U.S. EPA); U.S. Climate Extremes Index (NOAA); The Keeling Curve (Scripps Institution of Oceanography), Global Carbon Project.

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Droughts

• Measured in: DO-D4 (“abnormally dry” to “exceptional drought”)
• Where to check: U.S. Drought Monitor
• The latest: 12.2 percent of the United States is currently impacted by drought, with 0.34 percent of the United States currently in a D-3 “extreme drought.” 89 million people in the United States are currently impacted.
• Why it matters: Drought—a prolonged period of dry weather—occurs when there’s an imbalance between evaporation and precipitation. It’s the real-world consequence of rising temperatures and can have devastating impacts on human health, food availability, animals, and soil.
• What will help: It’s impossible to directly prevent a drought, especially since it’s closely tied to shorter-term climate oscillations, as well. Water conservation and planning are the only ways to mitigate drought impacts. However, more balanced precipitation and evaporation make drought less likely. You guessed it—greenhouse gas reduction will help in the long term.
• Who rang the alarm: Meteorological drought (Palmer, 1965)
• Learn more: Historical Palmer Drought Indices (NOAA); National Drought Mitigation Center (University of Nebraska – Lincoln); Drought.gov (National Integrated Drought Information System)

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Global Mean Sea Level (GMSL)

• Measured in: mm (millimeters) anomaly
• Where to check: NASA
• The latest: The current rate of change of the global mean sea level is a rise of 3.4 mm/year.
• Why it matters: Melting ice and a warming ocean mean more water and a rising sea level. Though the global sea level is also affected by short-term climate phenomena and geographic factors, it is closely linked to temperature. Sea levels rose consistently throughout the 20th century, leaving coastal regions more vulnerable to flooding, storm surges, and salt water seeping into freshwater aquifers and affecting plant and animal habitats.
• What will help: Three words: Reduce greenhouse gases.
• Who rang the alarm: Ice melt, sea level rise, and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2°C global warming could be dangerous (Hansen et al.)
• Learn more: Is Sea Level Rising? (National Ocean Service/NOAA); CU Sea Level Research Group (University of Colorado – Boulder); Global Average Absolute Sea Level Change, 1880-2014 (Open Knowledge International)

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Temperature

• Measured in: °F (degrees Fahrenheit) or °C (degrees Celsius)
• Where to check: NOAA/NCEI (U.S. | World)
• The latest: 2016 was the hottest year ever recorded, with global average temperatures reaching 1.69°F above the 20th-century average.
• Why it matters: Temperature is not only a relatively direct effect of global climate change—it’s also drives other phenomena like droughts, typhoons, hurricanes, wildfires, and habitat changes. Human health and food and water availability are also tied to temperature.
• What will help: Reducing greenhouse gases is the easiest way to drive down global temperature.
• Who rang the alarm: On the influence of carbonic acid in the air upon the temperature of the ground (Arrhenius, 1896)
• Learn more: U.S. and Global Temperature (U.S. EPA); U.S. Climate Extremes Index (NOAA); HadCRUT4 (University of East Anglia); Temperature Monitoring FAQ (NOAA)

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Sea Surface Temperature (SST)

• Measured in: °C (degrees Celsius) anomaly
• Where to check: NOAA/NCEI Extended Reconstructed Sea Surface Temperature (ESST)
• The latest: The average SST in 2016 was the warmest ever recorded, averaging 0.75: °C than last century’s average.
• Why it matters: Our oceans absorb heat, and the more they absorb, the warmer they get. This doesn’t just affect marine life, disrupting fish populations, fueling algal blooms, and killing coral. Higher sea surface temperatures also create more atmospheric water vapor. In turn, more water vapor drives a higher risk of extreme weather events, droughts, and disrupted storm patterns.
• What will help: The less heat the oceans must absorb, the cooler they’ll be. There’s only one way to accomplish that: Reduce greenhouse gases.
• Who rang the alarm: Temporal coherence in North Pacific sea-surface temperature patterns (Namias and Born, 1970)
• Learn more: Sea Surface Temperature Image Archive (Rutgers University); MODIS Satellite Sea Temperature (NASA); Sea Surface Temperature Trends (U.S. EPA)

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Arctic and Antarctic Sea Ice Extent

• Measured in: sq km (square kilometers) in which there is at least 15 percent ice
• Where to check: Sea Ice Index (National Snow and Ice Data Center)
• The latest: In January 2017, the Arctic sea ice extent was 13.4 million sq km—1.3 million sq kim less than the 1981-2010 mean for January. The Antarctic sea ice extent was 4.0 million sq km—0.6 million sq km less than the 1981-2010 mean for January.
• Why it matters: The polar ice caps have existed for millions of years. Not only are they a reliable indicator of climate change, but they reflect sunlight. That high albedo (reflectivity) helps deflect solar radiation, cooling off Earth. As the ice caps shrink, they stop cooling the poles. The less ice at the poles, the faster global warming will occur. In addition, the ice caps interact with animals (they’re habitat for everything from polar bears to penguins) and influence far-away weather. And as ice caps melt, they increase sea levels around the world.
• What will help: You know the score by now. The fewer greenhouse gases, the more protected our polar ice caps.
• Who rang the alarm: West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster (Mercer)
• Learn more: Arctic Sea Ice Minimum (NASA); Current State of the Sea Ice Cover (NASA); PIOMAS Arctic Sea Ice Volume Reanalysis (Polar Science Center)

source: popsci.com By Erin Blakemor