Earth, Two Degrees Warmer

Nothing says Friday like a hard-hitting report
on climate change! A new, pretty serious climate change forecast
came out this week in the journal Nature Climate Change, and it suggests there’s a 95% chance
the Earth’s average temperature will increase more than two degrees Celsius this century. And that isn’t great news — but there
might still be time to stop it. When you hear scientists talk about limiting
climate change, you usually hear something about how we shouldn’t let the Earth warm
by more than two degrees Celsius. What they mean by this is that we should make
sure that, this century, the Earth’s average temperature doesn’t get more than two degrees
hotter than pre-industrial levels — or the average global temperature before the late
1800s, which was around 14 degrees Celsius. A couple of degrees may not sound like a lot,
especially since the weather changes by more than that all the time. But the average global temperature is usually
really stable and doesn’t change by more than a degree or so. Two degrees is generally considered the major
benchmark because that would be enough of a temperature change to have serious, long-term
impacts on human life. It would lead to things like flooding, extreme
heatwaves, and droughts, which could make it harder for us to grow enough food, among
other problems, as if that wasn’t enough. But even keeping global warming under two
degrees isn’t really enough, because rising sea levels would be a problem for a lot of
small island nations. So there’s a stretch goal of 1.5 degrees. Unfortunately, we’re already one degree
warmer than pre-industrial days, so we don’t have much wiggle room. And on top of that, this new study isn’t
too optimistic. After running a lot of statistics, researchers
suggested there’s only a 5% chance the Earth won’t warm more than 2 degrees by 2100,
and only a 1% chance we’ll meet the more ambitious 1.5 degree goal. Instead, we’re probably looking at an increase
between two and five degrees — meaning heat waves, drought, storms, and rising sea levels
will all become a lot more severe. Everything from the quality of our air to
the price of our food will be affected, and those changes will get harder to reverse the
higher that temperature gets. Now, the results of this study aren’t that
surprising — they’re more or less in line with results of previous analyses. But they show we’re closer to the brink
that we’d like to believe. The statistics for the new study were based
on three factors: world population; per capita Gross Domestic Product, or GDP, which measures
a country’s economic output per person; and carbon intensity, which is the amount
of carbon dioxide emitted for every dollar a country generates. The data were based on trends from the past
fifty years, including new United Nations projections for the world population. The UN numbers predict the Earth’s population
will reach around 11 billion people by 2100, and that most of that increase will be in
Sub-Saharan Africa. But those countries use much less fossil fuel
than the rest of the world, and even by 2100, they’re expected to contribute only about
6% of the world’s CO2 emissions. So population growth will probably have a
small effect on greenhouse gas emissions. It isn’t really a great idea for countries
to start cutting their GDP, either, so if we want to lower greenhouse gas emissions,
the main thing to focus on is carbon intensity. Thanks to new emissions standards around the
world, carbon intensity should decrease by around 1.9% per year, which is a great start! But that still won’t be enough to stop the
planet from warming more than two degrees — and how fast carbon intensity continues
to drop will determine our future. Right now, there’s a wide range of possible
carbon intensities over the next century, but what actually happens will depend on technological
advances and environmental regulations. The forecast may not look great right now,
but it’s important to remember that this study doesn’t mean the planet will absolutely,
definitely warm by more than two degrees by 2100. The researchers say the two degree goal might
still be possible — but only, in their words, with, “major, sustained effort.” So, we’ve got a lot of work to do in the
next 80 years. Especially, all the scientists and engineers
out there, making this stuff happen. Thanks for watching this episode of SciShow
News. If you’d like to learn more about climate
science and what some scientists think could help us out, you can watch our video about
how to save Earth from … us.


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