REFRESHER ON THE BASICS OF CLIMATE CHANGE When we talk about climate change, we’re talking about the scientifically observable – and increasingly severe – changes in global climate patterns that became apparent in the mid-to-late twentieth century and can be attributed to the rising levels of atmospheric greenhouse gases (carbon dioxide, in particular) produced by human activities like burning fossil fuels. BUT SCIENTISTS DON’T AGREE THAT CLIMATE CHANGE IS CAUSED BY US, RIGHT? Wrong. According to NASA, 97 percent of climate scientists agree that global warming over the past century is “extremely likely due to human activities.” Among climate change deniers’ favorite arguments is that there is not “scientific consensus” that it is man-made. You’ll hear that phrase often, usually alongside talk that the current proven warming trend is part of a natural cycle. While the Earth has indeed experienced cycles of warming and cooling, scientists estimate that in the past it has typically taken around 5,000 years for the planet to recover – by warming between 4-7 degrees Celsius – after an ice age has ended. This makes the global average surface temperature increase of 1.1—1.6 degrees Fahrenheit (0.6—0.9 degrees Celsius) across just the twentieth century alone roughly eight times faster than the usual post-ice-age-recovery warming rate. And it’s a cycle that is only accelerating. Fifteen of the 16 hottest years on record globally have occurred this century. The phrase “scientific consensus” itself refers to the collective judgement of a scientific community, and while it implies agreement, it does not require unanimity. Ninety-seven percent of the climate science community agrees that climate change is real and that it is being caused by human activities such as our use of fossil fuels. Indeed, some scientists have asserted that the evidence linking human activities to climate change is as conclusive as the link between smoking and lung cancer. HOW CARBON POLLUTION CAUSES CLIMATE CHANGE. When carbon dioxide (CO2) is emitted into our atmosphere, it can hang around for a very long time. The more carbon pollution in the air, the more the sun’s energy gets trapped in our atmosphere as heat. Think about it like this: a build-up of carbon in the atmosphere is acting like a blanket around the Earth. As more heat gets in and less is able to escape, things keep getting hotter and the result impacts every element of our climate system. KEY INDICATORS. While there are several clear indicators that our climate is changing, the two most likely that require immediate attention might be sea-level rise and the increase in severe weather. Unlike many of the more gradual shifts associated with climate change, these are a little less abstract – in many cases, one can look out of the window and see these happening right now. 1.SEA LEVELS ARE RISING Sea levels have been rising for the past century. And the pace has increased in recent years as glaciers melt faster, Artic sea ice dwindles, and water temperatures increase. “Flooding will become more frequent as sea level rises,” according to the National Oceanic and Atmospheric Administration (NOAA). “In a sense, today’s flood will become tomorrow’s high tide, as sea level rise will cause flooding to occur more frequently and last for longer durations of time.” This is happening already in coastal cities in the US. In Florida alone, by the year 2060 (yeah, just 44 years from now), sea levels along the state’s coastline could rise an additional 9 inches to 2 feet. Imagine how similar sea-level rise will affect the almost 40 percent of the US population that lives in a coastal area. And let’s not forget that eight of the 10 largest cities in the world are near a coast. 2.THE WEATHER IS GETTING MORE SEVERE Speaking of the coast – do you love the warm water at the beach? So do hurricanes. As worldwide temperatures continue to increase, storms are able to absorb more energy from the resulting warmer oceans. Hurricanes and typhoons can arrive ashore with intense and damaging winds, very heavy rainfall, and major storm surges, often leading to devastating coastal damage and serious loss of life. As evaporation increases with warmer temperatures, there are some big implications for those further inland, as well. As the atmosphere gets warmer, it can hold more moisture. This greatly increases the risk of major flooding because, to put it simply, clouds brimming with ever-more evaporated water move over land and burst at the seams. And it’s not just hurricanes and floods either. Climate change has also been linked to an increase in many other weather extremes, such as heat waves and droughts. IS IT TOO LATE TO DO ANYTHING? Not at all. It’s true that even if we completely stopped emitting carbon pollution today, we’d continue to experience global warming for a considerable time. The pollution that has caused our current crisis stays in the atmosphere for hundreds of years – so yeah, it’s difficult to stop climate change in its tracks. But acting now to swiftly transition from dirty fossil fuels to clean energy can limit global warming to no more than 2 degrees Celsius (3.6 degrees Fahrenheit). Two degrees of warming could have significant impacts, there’s no denying. But if we do nothing and continue on the path we’re on, the global average temperature could rise 6 degrees Celsius (10.8 degrees Fahrenheit) by the end of the century. To say the difference between these two scenarios would be dramatic is perhaps quite literally the understatement of the century. If the global average surface temperature were to increase by 6 degrees Celsius above pre-industrial levels, according to author Mark Lynas (Six Degrees: Our Future on a Hotter Planet): Most of the planetary surface would be functionally uninhabitable. Agriculture would cease to exist everywhere, apart for the polar and sub-polar regions, and perhaps the mid-latitudes for extremely heat-tolerant crops. … It's pretty much equivalent of a meteorite striking the planet, in terms of the overall impacts. Seems rough. Seems like the sort of thing we should do everything in our power to avoid, no? The good news is that we can. And world leaders seem to finally agree that urgent action is a necessity. But there is a lot of work left to do – work that could easily be disrupted. A bright, sustainable future for our planet is finally in sight, but only if we support leaders who work to make climate solutions a reality. This is where you come in. Join people all around the world in speaking up for clean energy so that when our leaders take action to cut emissions and stop rising global temperatures, we’re with them all the way. Wondering what you can do to solve the climate crisis? Become a @ClimateReality Leader and learn to #LeadOnClimate http://bit.ly/2puw6VH