We know. Global warming is discouraging. So here's a place to start: 17 frequently asked questions with some direct answers.
Part 1 What is happening?
1. Climate change? Global warming? What do we call it?
They are both accurate, but they mean different things.
You can think of global warming as a type of climate change. The broader term encompasses changes beyond warmer temperatures, such as changing rainfall patterns.
President Trump claimed that scientists stopped referring to global warming and started calling it climate change because "the weather has been so cold" in winter. But the claim is false. Scientists have used both terms for decades.
2. How much is the Earth warming?
Two degrees is more significant than it sounds.
As of early 2017, the Earth had warmed by about 2 degrees Fahrenheit (more than 1 degree Celsius) since 1880, when records began on a global scale. The number may sound low, but on average over the surface of an entire planet, it is actually high, which explains why so much of the world's land ice is starting to melt and the oceans are rising at a rapid rate. If greenhouse gas emissions continue unchecked, scientists say global warming could ultimately exceed 8 degrees Fahrenheit, undermining the planet's ability to support a large human population.
3. What is the greenhouse effect and how does it cause global warming?
We have known it for more than a century. For real.
In the 19th century, scientists discovered that certain gases in the air trapped and slowed down heat that would otherwise escape into space. Carbon dioxide is a major player; with none of that in the air, Earth would be a frozen wasteland. The first prediction that the planet would warm when humans released more gas was made in 1896. The gas has risen 43 percent above the pre-industrial level so far, and the Earth has warmed about the amount that scientists predicted.
4. How do we know that humans are responsible for the increase in carbon dioxide?
Strong evidence, including studies that use radioactivity to distinguish industrial emissions from natural emissions, shows that the extra gas comes from human activity. Carbon dioxide levels naturally rose and fell in the past long ago, but those changes took thousands of years. Geologists say that humans are now pumping gas into the air much faster than nature did.
5. Could natural factors be the cause of the warming?
In theory, they could be. If the sun started emitting more radiation, for example, that would definitely heat up the Earth. But scientists have carefully analyzed the natural factors known to influence planetary temperature and found that they are not changing enough. Warming is extremely rapid on the geological time scale, and no other factor can explain it, as well as human emissions of greenhouse gases.
6. Why do people deny the science of climate change?
Mainly by ideology.
Instead of negotiating on climate change policies and trying to orient them more market-driven, some political conservatives have taken the approach of blocking them by trying to undermine the science.
President Trump has at times claimed that scientists are involved in a global hoax to mislead the public, or that global warming was invented by China to disable American industry. The arguments of climate deniers have become so strained that even the oil and coal companies have publicly distanced themselves, although some still help fund the campaigns of politicians who defend these views.