Originally published on The Climate Reality Project.
How do we know our climate is changing drastically due to human activity, rather than just going through a normal period of flux? Let’s look at five major changes scientists have seen in our climate system to help set the record straight.
1. Air temperatures over land are rising.
It’s clear that weather stations on land show average air temperatures are rising, and as a result, the frequency and severity of droughts and heat waves are increasing. Intense droughts can lead to destructive wildfires, failed crops, and low water supplies, many of which are deeply affecting southern areas of the United States and other parts of the world.
2. Air temperatures over oceans are rising.
Roughly 70 percent of the world is covered by oceans. So you can understand how hotter air over our oceans could make a big difference in the climate system.
It’s simple, as the air near the surface of the oceans gets warmer, more water evaporates. The result? Potentially stronger tropical storms, more extreme precipitation events, and more flooding.
3. Glaciers are melting.
The disappearance of glaciers is one of the clearest signs of climate change. People who rely on melting glaciers for water are facing shortages, and in many regions, the situation is only getting worse.
In a world unaffected by climate change, glacier mass stays balanced, meaning the ice that evaporates in the summer is fully replaced by snowfall in the winter. However, when more ice melts than is replaced, the glacier loses mass. And the people who depend on melting ice for water to support their farming and living needs are deeply affected.
4. Arctic sea ice is shrinking.
Satellite images from space show that the area covered by sea ice in the Arctic is shrinking, continuing a downward trend for the past 30 years. As with glaciers, there’s a seasonal rhythm (or supposed to be) at work. The Arctic ice cap grows each winter when there’s less sunlight, and shrinks each summer when days are longer and warmer, reaching its lowest point of the year in September.
Previously, this cycle of melting and freezing has more or less balanced out. But with temperatures rising, we’re seeing more ice melt in the summer than forms in the winter. The result is that some research suggests that the Arctic could lose almost all of its summer ice cover by later in the century.
5. Sea levels are rising.
Sea levels have been rising for the past century. And the pace has only increased in recent years, as glaciers melt faster and water temperatures increase (causing oceans to expand). You can imagine how this would affect the almost 40 percent of the US population that lives in a highly populated coastal area. Let’s not forget that eight of the 10 largest cities in the world are near a coast.
Consider how many millions of people are at risk as sea levels rise, storms intensify, and more extreme flooding occurs. Additionally, as sea levels rise, salt water begins intruding into freshwater aquifers, many of which support human communities and natural ecosystems.
Here’s Where You Come In.
Few global trends have inspired so much public confusion and scientific certainty at the same time as climate change (and we can thank the fossil fuel industry for that). Yes, Earth has gone through many shifts in cooling and warming driven by natural factors like the sun’s energy or variations in its orbit. But the trend scientists have seen, particularly over the past 50 years, is unmistakable. Human activity is causing climate change.
That’s why, now more than ever, we need leaders who know climate change is real and are making climate solutions a top priority. One of the best things you can do to make your voice heard as a climate activist is to support these leaders – sign the Reality Pledge now!
Reprinted with permission.
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