What Is Global Warming – Climate Change & Extreme Weather


What is global warming Glaciers are melting, sea levels are rising, cloud forests are dying, and wildlife is scrambling to keep pace. It has become clear that humans have caused
most of the past century’s warming by releasing heat-trapping gases as we
power our modern lives. Called greenhouse gases, their levels are higher now than at any time
in the last 800,000 years. We often call the result global warming, but it is causing a set of changes to the Earth’s climate, or long-term weather patterns, that varies from place to place. While many people think of global warming
and climate change as synonyms, scientists use “climate change” when
describing the complex shifts now affecting our planet’s weather and climate systems in part because some areas actually
get cooler in the short term. Climate change encompasses not only rising average
temperatures but also extreme weather events, shifting wildlife populations and habitats, rising seas, and a range of other impacts. All of those changes are emerging as humans continue to
add heat-trapping greenhouse gases to the atmosphere, changing the rhythms of climate that all living things
have come to rely on. What will we do, what can we do, to slow this human caused warming? How will we cope with the changes we’ve
already set into motion? While we struggle to figure it all out, the fate of the Earth as we know it coasts, forests, farms and snow-capped mountains hangs in the balance. Understanding the greenhouse effect The “greenhouse effect” is the warming that happens when
certain gases in Earth’s atmosphere trap heat. These gases let in light but keep heat from escaping, like the glass walls of a greenhouse, hence the name. Sunlight shines onto the Earth’s surface, where the energy is absorbed and then radiate
back into the atmosphere as heat. In the atmosphere, greenhouse gas molecules trap some of the heat, and the rest escapes into space. The more greenhouse gases concentrate in the atmosphere, the more heat gets locked up in the molecules. Scientists have known about the greenhouse effect since 1824, when Joseph Fourier calculated that the Earth would
be much colder if it had no atmosphere. This natural greenhouse effect is what keeps the
Earth’s climate livable. Without it, the Earth’s surface would be an average of
about 60 degrees Fahrenheit cooler. Aren’t temperature changes natural? Human activity isn’t the only factor that
affects Earth’s climate. Volcanic eruptions and variations in
solar radiation from sunspots, solar wind, and the Earth’s position relative to the sun also play a role. So do large-scale weather patterns such as El Niño. But climate models that scientists use to monitor
Earth’s temperatures take those factors into account. Changes in solar radiation levels as well as minute particles
suspended in the atmosphere from volcanic eruptions, for example, have contributed only about two percent to
the recent warming effect. The balance comes from greenhouse gases and other
human-caused factors, such as land use change. The short timescale of this recent warming
is singular as well. Volcanic eruptions, for example, emit particles that temporarily cool the Earth’s surface. But their effect lasts just a few years. Events like El Niño also work on fairly
short and predictable cycles. On the other hand, the types of global temperature fluctuations that
have contributed to ice ages occur on a cycle of hundreds of thousands of years. For thousands of years now, emissions of greenhouse gases to the atmosphere
have been balanced out by greenhouse gases that are naturally absorbed. As a result, greenhouse gas concentrations and temperatures
have been fairly stable, which has allowed human civilization to flourish
within a consistent climate. Now, humans have increased the amount of
carbon dioxide in the atmosphere by more than a third since the Industrial Revolution. Changes that have historically taken thousands of years are
now happening over the course of decades. Why does this matter? The rapid rise in greenhouse gases is a problem
because it’s changing the climate faster than some living things can adapt to. Also, a new and more unpredictable climate poses
unique challenges to all life. Historically, Earth’s climate has regularly shifted between
temperatures like those we see today and temperatures cold enough to cover much of
North America and Europe with ice. The difference between average global temperatures today
and during those ice ages is only about 9 degrees Fahrenheit (5 degrees Celsius), and the swings have tended to happen slowly, over hundreds of thousands of years. But with concentrations of greenhouse gases rising, Earth’s remaining ice sheets such as Greenland and
Antarctica are starting to melt too. That extra water could raise sea levels significantly, and quickly. By 2050, sea levels are predicted to rise between one
and 2.3 feet as glaciers melt. As the mercury rises, the climate can change in unexpected ways. In addition to sea levels rising, weather can become more extreme. This means more intense major storms, more rain followed by longer and drier droughts a challenge for growing crops changes in the ranges in which plants and animals can live, and loss of water supplies that have historically
come from glaciers.

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