Climate change has always happened on Earth, which is clearly seen in the geological record. For the last three weeks, we’ve covered natural climate change: from orbital parameters to the Sun to volcanoes to the oceans and internal variability in the climate system. Natural climate change plays the long game – taking hundreds to thousands of years to manifest change. It is the rapid rate and the magnitude of climate change occurring now that is of great concern worldwide. So, what/who is responsible for that?

The story begins with the Industrial Revolution, when human activity, like using gasoline for driving cars and using coal for heating buildings, started to add more greenhouse gases to the atmosphere. These gases (carbon dioxide and methane, for example), act like a blanket around the Earth, trapping heat and raising temperatures. Without the gases, surface temperatures would be too cold to sustain life, as we know it on Earth. But too high of a concentration of these gases, and temperature goes way up. The Earth is now about 1.1°C warmer than it was in the late 1800s, with the last decade (2011-2020) as the warmest on record. Many people think climate change mainly means warmer temperatures, but temperature rise is only the beginning of the story. The Earth is a system – everything is connected – so changes in one area can influence changes in all others. The consequences of climate change include intense droughts (the Western United States is experiencing its worst drought in over 1000 years), water scarcity, severe fires, rising sea levels, flooding, melting polar ice, catastrophic storms and declining biodiversity.

With all the bad news, is there any good? Yes! Switching from fossil fuels to renewables like solar or wind will reduce the emissions driving climate change. But we have to start right now. While a growing coalition of countries is committing to net zero emissions by 2050, about half of emissions cuts must be in place by 2030 to keep warming below 1.5°C. Why that temperature? If we exceed it, coral reefs face almost complete die-off; “unheard of” storms become more common; and melting ice leads to flooded coastal cities. This is the future facing us. Already we are seeing some of these effects – imagine them amplified. What kind of quality of life does that lead to? We have the intellect and the technology to do this – now we need the will.

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