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- It's cold and it's snowing! Does that mean climate change isn’t real?
- Aren’t there some scientists who disagree about climate change?
- Isn't climate change a natural thing?
- Do people farts contribute to climate change, too?
- Is eating meat part of the problem?
- Are aerosol spray cans that destroy the ozone layer part of the problem?
- Hasn’t there been global warming before?
- Why can’t all the extra greenhouse gases just escape through the hole in the ozone layer?
- Is there anything GOOD about global warming?!
- Could global warming cause an ice age, like in The Day After Tomorrow?
One day, or week or even month of unusually cold weather doesn’t mean climate change isn’t happening. Nor does one hot week, summer or even year, prove it’s real.
It's like the Red Sox: Sure, they lose a game or two sometimes, but when you look at the big picture, they win a lot more than they lose (So says Reb, a big Red Sox fan.) You gotta look at least 5-10 years to really see climate change.
Or, as one student told us: “Climate is the clothes you have in your closet. Weather is what you wear that day.”
Not a lot! 97% of scientists agree that climate change is real and it's caused by people. It’s pretty hard to get scientists to agree 100% about almost anything! Scientists by nature and by their job are pretty skeptical people. They’re always looking for more data. If one scientist could come along and prove that something besides people was causing climate change (because we know it’s happening!), then other scientists would have to reconsider. But that hasn’t happened yet. In fact, human-produced greenhouse gases are the only thing that does explain climate change.
Don’t we wish that were the case! Climate change has been occurring naturally for as long as the Earth has been around and the factors that cause climate to change naturally (like the sun and volcanoes) are still at work today. However, their effects are pretty tiny when compared to the warming caused by people burning fossil fuels. It’s more like we’re causing almost all the warming and natural processes have been pushed into the background.
Scientists spend a lot of time studying the natural forces of climate change, like the sun, and they know from satellite measurements almost exactly how much solar radiation the sun puts out from year to year. They also have a good understanding of what that translates to in terms of temperatures on Earth. The only way computer models can make temperatures over the last 60 years go up the way they have been is when they include CO2 from human activity. Without that, temperatures would have stayed pretty flat for the last half-century or so.
Not in the same way cow burps and farts do! People farts don’t produce nearly as much methane as cow farts (and especially burps) do — most human farts actually contain no methane at all (Miller et al 1982).
That’s because cows are ruminants and digest their food differently than humans. It’s a process called enteric fermentation in which cows break down their food in a four-part stomach. This system, as well as when cows chew their cud (spit up their food and chew it again — yum!), lets cows eat tough, fibrous material for food, but it also produces a lot of methane. And did you know? About 95% of the methane from cows is actually from the burps, not the farts.
For those of us who love a burger, sadly, the answer is yes. Eating red meat definitely increases your carbon footprint. People around the world are eating more and more meat, which means that we are raising more livestock than ever before. More livestock means more methane emissions from cows. Meat is also a very resource-intensive food, requiring lots of energy, land, water and feed, which makes the climate impact of eating meat bigger than almost all other foods.
Actually, no! The hole in the ozone layer is a totally different problem than global warming. It’s easy to get them confused though, since they both involve gases in our atmosphere. The ozone layer is in the upper part of the atmosphere (the stratosphere) and it helps to block out ultraviolet (UV) radiation coming from the sun from getting to Earth and doing things like hurting our eyes and causing skin cancer.
The hole in the ozone layer over Antarctica was created by human-produced chlorofluorocarbons (CFCs) that came from things like aerosol cans and air-conditioners and refrigerators. This was a big problem in the 1970s and 1980s. But in 1987, the world got together and passed the Montreal Protocol, which banned CFCs and replaced them with HCFCs and HFCs, which don’t destroy the ozone layer. (HFCs are a really long-lived greenhouse gas, though, so that’s not so good.) So now the hole in the ozone layer is getting better and should be all gone by the end of the century. Wish the same was true about climate change!
Yes! The Earth has warmed naturally before.
But, just because it’s happened in the past, doesn’t mean that what’s happening today must be natural, too. We’re taking natural materials — fossil fuels buried in the Earth, which took millions of years to form — and we’re using them in a pretty unnatural way: burning them and releasing that hidden carbon back into the system in the form of CO2 so fast that the Earth doesn’t know how to handle it.
Wouldn’t that be great? Sadly, that’s not how it works. The greenhouse gases stick around in the atmosphere for the same reason that the rest of the atmosphere is here and for the same reason you and I are stuck to the Earth’s surface — gravity. Gravity holds all those millions of tiny molecules that make up our atmosphere close to the planet’s surface. This is a good thing, too, because we’d have no air to breathe without it!
There are a few things – more crop productivity and the opening up of the Northwest Passage are two. But these are also balanced out by some serious negatives on the other side. Increased crop productivity in more northern countries, like the U.S. and Canada, won’t make up for decreased agriculture in other countries, particularly Africa, that will become drier. And the opening of the Northwest Passage (the trade route through the Canadian Arctic) is fraught with complications — oil spills in this fragile environment being one of the most concerning.
And why is it all bad news? Primarily because climate change is happening too quickly for natural and human systems to adapt. A second reason is that climate change puts weather on steroids — the big storms, droughts, heat waves and fires get bigger. It’s the extra energy in Earth’s climate system from extra greenhouse gases that does that.
Cheers to The Day After Tomorrow for bringing climate change and the term “paleoclimatologist” into the public attention. Being a Hollywood blockbuster, they did exaggerate a bit (or more than a bit). But the movie is based on some real science.
The premise of the movie is that global warming could cause the next ice age. This is how it could happen: As more and more ice melts in the Arctic, more fresh water runs into the North Atlantic Ocean. The North Atlantic is a key spot for the ocean’s circulation system, which distributes heat from the equator to the poles. Here, the seawater gets both cold and salty enough to become really dense and sink to the bottom of the ocean. If enough fresh water from melting glaciers flows into the North Atlantic, this would make the seawater less salty and less dense, so that it couldn’t sink anymore. This could slow down — or even shut down — the ocean circulation system that brings heat from the tropics to the high latitudes. This would make the Arctic a lot colder and it could start growing a big ice cap, which would, in turn, reflect more sunlight back out to space and make the Earth cool even more, spiraling us into an ice age.
The slowdown and shutdown of the ocean circulation system is something that scientists do worry about. Global warming is predicted to make a small dent in the power of that system in the next few hundred years, but not nearly to the point of shutting it down and causing an ice age. So, that’s not really anything to worry about for several hundred years yet.