First, they need to know what the potential local impacts will be at the scales of counties to cities. Second, policymakers need to understand uncertainties in the ranges of probable climate impacts and responses. Even regions that are proactive in setting adaptation policies, such as California, lack information about the ever-changing risks of extreme warming, fires and rising seas. Research must be integrated across fields and stakeholders — urban planners, public-health management, agriculture and ecosystem services.
Adaptation strategies should be adjustable if impacts unfold differently. More planning and costing is needed around the worst-case outcomes. Understand options for rapid response. Climate assessments must evaluate quick ways of lessening climate impacts, such as through reducing emissions of methane, soot or black carbon and HFCs.
Their atmospheric lifetimes are short — in the range of weeks for soot to about a decade for methane and HFCs. Slashing these pollutants would potentially halve the warming trend over the next 25 years There has been progress on this front.
Various climate engineering options should be on the table as an emergency response. If global conditions really deteriorate, we might be forced to extract large volumes of excess CO 2 directly from the atmosphere. An even faster emergency response could be to inject aerosols into the atmosphere to lower the amount of solar radiation heating the planet , as air pollution does.
This option is hugely controversial, and might have unintended consequences, such as altering rainfall patterns that lead to drying of the tropics.
So research and planning are crucial, in case this option is needed. Until there is investment in testing and technical preparedness — today, there is almost none — the chances are high that the wrong kinds of climate-engineering scheme will be deployed by irresponsible parties who are uninformed by research For decades, scientists and policymakers have framed the climate-policy debate in a simple way: scientists analyse long-term goals, and policymakers pretend to honour them.
Those days are over. Serious climate policy must focus more on the near-term and on feasibility. It must consider the full range of options, even though some are uncomfortable and freighted with risk.
Intergovernmental Panel on Climate Change. Global Warming of 1. Earth Syst. Data 10 , — Article Google Scholar. Smith, D. Karplus, V. Natl Acad. USA , — PubMed Article Google Scholar. Burnett, R. An indicator of changes in the Arctic sea ice minimum over time. Arctic sea ice extent both affects and is affected by global climate change.
The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since The U. The official website for NASA's fleet of Earth science missions that study rainfall and other types precipitation around the globe. How much do you know about how water is cycled around our planet and the crucial role it plays in our climate?
Graphic about how increased greenhouse gases from human activities result in climate change and ocean acidification. Santer et.
Ramaswamy et. Westerhold et. In , Joseph Fourier calculated that an Earth-sized planet, at our distance from the Sun, ought to be much colder. He suggested something in the atmosphere must be acting like an insulating blanket. In , Eunice Foote discovered that blanket, showing that carbon dioxide and water vapor in Earth's atmosphere trap escaping infrared heat radiation.
In the s, physicist John Tyndall recognized Earth's natural greenhouse effect and suggested that slight changes in the atmospheric composition could bring about climatic variations. In , a seminal paper by Swedish scientist Svante Arrhenius first predicted that changes in atmospheric carbon dioxide levels could substantially alter the surface temperature through the greenhouse effect.
Levitus, S. NCEI ocean heat content, temperature anomalies, salinity anomalies, thermosteric sea level anomalies, halosteric sea level anomalies, and total steric sea level anomalies from to present calculated from in situ oceanographic subsurface profile data NCEI Accession Version 4.
Heat stored in the Earth system: where does the energy go? Velicogna, I. National Snow and Ice Data Center.
In , the Swedish chemist Svante Arrhenius discovered that humans could enhance the greenhouse effect by making carbon dioxide , a greenhouse gas. He kicked off years of climate research that has given us a sophisticated understanding of global warming. Levels of greenhouse gases have gone up and down over the Earth's history, but they had been fairly constant for the past few thousand years.
Global average temperatures had also stayed fairly constant over that time— until the past years. Through the burning of fossil fuels and other activities that have emitted large amounts of greenhouse gases, particularly over the past few decades, humans are now enhancing the greenhouse effect and warming Earth significantly, and in ways that promise many effects , scientists warn.
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.
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.
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. 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.
Because of the low atmospheric pressure, and with little to no methane or water vapor to reinforce the weak greenhouse effect, Mars has a largely frozen surface that shows no evidence of life. Too much greenhouse effect: The atmosphere of Venus, like Mars, is nearly all carbon dioxide. But Venus has about , times as much carbon dioxide in its atmosphere as Earth and about 19, times as much as Mars does , producing a runaway greenhouse effect and a surface temperature hot enough to melt lead.
The above graph compares global surface temperature changes red line and the Sun's energy that Earth receives yellow line in watts units of energy per square meter since Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious.
Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century. Images of Change. Explore a stunning gallery of before-and-after images of Earth from land and space that reveal our home planet in a state of flux. Climate Mobile Apps.
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