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  • Cloudy climate change. How clouds affect earth's temperature

  • Earth's average surface temperature has warmed by point eight celsius since 1750

  • when carbon dioxide concentration in the atmosphere have doubled

  • which is expected before the end of the twenty first century

  • Researchers project global temperature will have raisen by 1.5 to 4.5 degrees Celsius

  • if the increase is near the low end 1.5 celsius

  • then we're already half way there

  • we should be more able the adopt with some regions are becoming dryer and less productive

  • but others becoming warmer wetter and more productive

  • on the other hand, a rise of 4.5 degree celsius would be similar in magnitude

  • to the warming that's occur since the last glacier maximum, 22 thousand years ago

  • when most of the north America was under ice sheet 2 kilometer's thick

  • so that would represent the dramatic change of climate

  • so it's vitally important for scientists to predict the change in temperature

  • with as much precision as possible. so the society can plan for the future

  • the present range of uncertainty simply too large to be confident of how best to respond to climate change

  • but this estima to 1.5 to 4.5 celsius for doubling the carbon dioxide hasn't change in 35 years

  • why haven't we been able to narrow it down?

  • the answer is we don't yet understand aerosols in clouds well enough

  • but the new experimentists is tackling the problem

  • in order to predict how the temperature will change. Scientist need to know some called earth climate sensitivity.

  • the temperature change in response to radiative forcing

  • A radiat forum set is a temperate imbalace between the energy receive from the sun

  • and energy radiate back out to space like the imbalance cause by increase of green house gases

  • to correct imbalance of warms up or cools down,

  • we can determine earth climate sensitivity from the experiment we've already performed in industrial age since 1750.

  • and then the uses number to determine how much more it will warm to varies projected radiated forcing in the twenty first century

  • to do this, we need to know two things.

  • First, the global temperature rise since 1750.

  • And second, the radiative forcing of the present day climate relative to the pre-industrial climate

  • for the radiative forcing we know that human activities has been increased green house gases in the atmosphere which warm the planet

  • but our activities have at the same time increase the amount of aerosols particles in clouds which have cooled the planet.

  • Pre-industrial green house gas concentrations are well measured

  • From bubbles trap in ice course of tent in Greenland and Antarctic.

  • So the greenhouse gas forcings are precisely known.

  • But we have no way of direct recongnition how cloudy it was in 1750.

  • And that’s the main source of uncertainty in earth climate sensitivity.

  • To understand pre-industrial cloudy is we must use computer models

  • that reliably simulate the process is responsible for forming nuclei in clouds.

  • Now, to most people aerosols are the things to make your hair stick.

  • But that’s only one type of aerosols.

  • Atmospheric aerosols are tiny liquid or solid particles suspended in the air.

  • There are either primary from dust sea spray salt, burning biomass

  • Or secondary formed by gas to particle conversion in the atmosphere

  • Also known as particle nucleation.

  • Aerosols are everywhere in the atmosphere. And they can block out the sun and polluted urban environments.

  • Or bath distant mountain in blue pace.

  • More importantly the cloud droplet cannot form without an aerosol particle seed.

  • So without aerosol particle, therell be no clouds.

  • And without clouds, there will be no fresh water.

  • The climate will be much hotter. And there will be no life.

  • So we owe our existence to aerosol particles.

  • However, despite their importance how aerosol particles form in the atmosphere

  • aren’t very effect on clouds and poorly understood.

  • Even the vapor is responsible for aerosol particle formation and not well established.

  • Because at present in only might mute amount near one molecule per million million molecules are there.

  • This lack of understanding is the main reason for the large uncertainty in climate sensitivity.

  • And the corresponding wild range of future climate projections.

  • However, an experiment under way is certain named surprisingly cloud has manage to build a steel vessel

  • That’s large enough and has low enough contamination that aerosol formation can

  • For the first time, be measured under tightly controlled atmosphere condition in the bar of tray.

  • In the first five years of operation, cloud has identified the vapor

  • responsible for the aerosol formation in the atmosphere.

  • Which includes sulfuric acid, ammonia amines and biogenic vapours from trees.

  • Using an eye and icing particle bean for the certain proton synchrotron

  • Cloud is also investigating if galactic cosmic rays enhance the formation of aerosols in clouds.

  • This has been suggested as possible unaccounted natural climate forcing agent

  • since the flux of cause midgrade raining down in the atmosphere.

  • There is with solar activity.

  • So cloud is addressing two big questions:

  • Firstly, how cloudy was the pre-industrial climate?

  • And hence, how much have clouds changed due to human activities?

  • That knowledge will help sharpen climate projections in the 21st century.

  • And simply, could the puzzling observation of solar climate variability in the pre-industrial

  • be explained by an influence of galactic cosmic rays on the clouds?

  • Ambitious but realistic goals, when your heads in the clouds

Cloudy climate change. How clouds affect earth's temperature

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TED-ED】雲の気候変動。雲が地球の気温に与える影響 - Jasper Kirkby (【TED-Ed】Cloudy climate change: How clouds affect Earth's temperature - Jasper Kirkby)

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    Go Tutor に公開 2021 年 01 月 14 日
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