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HOT Climate Change Questions


What difference can a few degrees make?

Earth's temperature has gone up 1.4 degrees in the last century. That may not sound like a big deal. But if you've ever fallen through melting ice on a skating pond, you know what difference a few degrees can make.

As Earth heats up, the Sun sucks water from the land, creating droughts in some places. Warmer air absorbs the water like a sponge and then dumps it, big time, flooding other places.

We're talking about the whole planet, so a few degrees averaged over the whole globe over a year's time or longer may not seem like much, but:

  • A few globally averaged degrees translate into many more local and regional heat waves, bringing 100-degree days to places not prepared to deal with extreme heat, like Buffalo and Seattle. The warmer atmosphere will also mean heavier rains and snows when it storms, rising sea levels that threaten coastal cities, more severe dry spells where it's dry, and more wildfires.
  • A few degrees on a summer day can make Chicago feel like St. Louis and St. Louis feel like Dallas.
  • Some areas are warming more than others, as climate scientists predicted. We're seeing dramatic temperature increases in the Arctic, where where year-round sea ice may soon vanish in summer. Hunters who depend on sea mammals for subsistence are now literally on thin ice and the long-term survival of polar bears is in question. Melting permafrost threatens the natural environment, disrupts transportation as roads become impassable, and endangers people as buildings crack and buckle.
  • Timing matters, too. Spring arrives a bit earlier than it used to in many places. If all plants and animals adapted to this change at the same pace, it might not be such a problem. But uneven shifts in the seasons are disrupting the balance between predators and their prey. Already, some birds flying north are having a hard time on arrival because the bugs they eat emerged earlier than in the past, leaving less food available for the hungry birds and their offspring.

Can people really change the climate?

Earth's climate works like a seesaw—hot stuff on one side, cold stuff on the other. The Sun, icebergs, oceans—even small clouds keep the planet's temperatures in balance.

Add weight to one side of the seesaw, and things go whoah! pretty quickly. For instance, greenhouse gases trap heat. Each second, cars and factories add more than a million pounds of greenhouse gases to the atmosphere. That's a lot of weight to add to one side of a seesaw.

It's true that the greenhouse gases we produce represent just a tiny fraction of the atmosphere, but

  • The atmosphere is in balance and even the small amount we add to the atmosphere by driving our cars, heating or cooling our homes, and producing products in factories can tip the balance—like adding a little extra weight to one side of a seesaw.
  • Scientists using some of the most powerful supercomputers in the world have studied whether variations in the Sun's intensity, volcanic eruptions, or other natural factors can account for the warming over the last century. They have found that these natural factors would have kept our climate approximately steady. It's because of the extra carbon dioxide and other greenhouse gases we've put in the atmosphere that the climate has warmed. (For more about the NCAR study, see: Don't changes in the Sun, like sunspots, explain global warming?)
  • Ever since the late 19th century, scientists have known that carbon dioxide and certain other gases trap heat in the atmosphere. It's a basic scientific process. Our knowledge of physics and chemistry, our supercomputing studies, and our observations of what's actually happening in the world all point in one direction: human production of greenhouse gases is warming our planet.

Can't we wait and fix the climate if things get really bad?

When you're driving a car, you can slow down just like that. When you're driving a planet's atmosphere, you need to slow down decades ahead.

Today's greenhouse gases will affect Earth's climate for another hundred years. We're committing ourselves to a long, hot future. How hot depends on how fast we put on the brakes.

Most climate scientists agree that we have enough evidence, despite remaining uncertainties, to start taking precautions now. The longer we wait, the more damage we'll be dealing with:

  • Greenhouse gases can stay in the atmosphere for 100 years or more. A sizeable chunk of what we emit today will still be around when our great grandchildren are growing up. Even if we were to stop all emissions today, the world will continue to warm from the gases we've already added to the atmosphere. Adding even more could push some ecological systems beyond the point of recovery.
  • Scientists have studied technological fixes, such as shading the planet from some incoming sunlight. But it's not clear whether those technologies would work. Even if they did, they could cause environmental havoc, such as damaging the ozone layer or leaving some parts of the world with too little sunlight or not enough rainfall to grow food. We're already conducting a dangerous experiment by warming the climate. There may be other risks we can't anticipate from trying to artificially cool it.
  • Blocking the Sun's energy without decreasing our greenhouse gas production won't eliminate the damaging chemical effects of carbon dioxide. The more carbon dioxide the oceans absorb, the more acidic they become, and this change is killing coral reefs and other marine life.

It's cold here today—whatever happened to global warming?

Most of us tend to notice the things that are in front of us, right now. But climate change happens over many years, even centuries. And to measure those changes, you need to look at the globe as a whole.

So, yeah, it might be cold where we are today. But when we look at the Earth as a whole, the climate is warmer than it used to be on most days. And the forecast for the rest of the century is for a lot more heat to come.

We study climate globally over decades, centuries, and millenia. But people live locally, and our memories don't last quite so long.

  • If the road you drive to work is free of traffic one morning, that doesn't mean your city's traffic problems have gone away. So while you might have a cool summer or a major snow storm where you live, you might not hear about the heat wave half a world away. When we add up and take the average of all the observations of air and ocean temperatures around the world over time, there's a clear warming trend.
  • Even in a warming world, there will still be cold and warm periods. But overall we can expect more unusually high temperatures. Climate change is like loading the dice: the odds are being shifted to more warmer days and nights.



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