There is great debate among many people, and sometimes in the news, on whether global warming is real some call it a hoax. But climate scientists looking at the data and facts agree the planet is warming.
Instrumental temperature record Annual thin lines and five-year lowess smooth thick lines for the temperature anomalies averaged over the Earth's land area red line and sea surface temperature anomalies blue line averaged over the part of the ocean that is free of ice at all times open ocean.
Two millennia of mean surface temperatures according to different reconstructions from climate proxieseach smoothed on a decadal scale, with the instrumental temperature record overlaid in black.
Multiple independently produced datasets confirm that from to the global average land and ocean surface temperature increased by 0. The rest has melted ice and warmed the continents and the atmosphere.
Regional effects of global warming and Cold blob North Atlantic Difference between average temperature in — compared to the period, showing strong arctic amplification.
Global warming refers to global averages. It is not uniform around the world: Although more greenhouse gases are emitted in the Northern than in the Southern Hemisphere, this does not contribute to the difference in warming because the major greenhouse gases persist long enough to diffuse within and between the two hemispheres.
One climate commitment study concluded that if greenhouse gases were stabilized at year levels, surface temperatures would still increase by about 0. Some of this surface warming would be driven by past natural forcings which have not yet reached equilibrium in the climate system.
Some climatologists have criticized the attention that the popular press gives to "warmest year" statistics.
Attribution of recent climate change By itself, the climate system may generate random changes in global temperatures for years to decades at a time, but long-term changes emanate only from so-called external forcings. Greenhouse gasGreenhouse effectRadiative forcingCarbon dioxide in Earth's atmosphereand Earth's energy budget The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in a planet's atmosphere warm its lower atmosphere and surface.
It was proposed by Joseph Fourier indiscovered in by John Tyndall was first investigated quantitatively by Svante Arrhenius in and the hypothesis was reported in the popular press as early as The rest of this increase is caused mostly by changes in land-use, particularly deforestation.
According to professor Brian Hoskinsthis is likely the first time CO2 levels have been this high for about 4. Attributions of emissions due to land-use change are subject to considerable uncertainty.
Atmospheric particles from these and other sources could have a large effect on climate through the aerosol indirect effect. Global dimminga gradual reduction in the amount of global direct irradiance at the Earth's surface, was observed from until at least They exert a cooling effect by increasing the reflection of incoming sunlight.
Removal by clouds and precipitation gives tropospheric aerosols an atmospheric lifetime of only about a week, while stratospheric aerosols can remain for a few years. Carbon dioxide has a lifetime of a century or more, and as such, changes in aerosols will only delay climate changes due to carbon dioxide.
Sulfate aerosols act as cloud condensation nuclei and thus lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets, a phenomenon known as the Twomey effect.
Indirect effects of aerosols represent the largest uncertainty in radiative forcing. Atmospheric soot directly absorbs solar radiation, which heats the atmosphere and cools the surface.
Contribution of natural factors and human activities to radiative forcing of climate change. Milankovitch cycles The tilt of the Earth's axis and the shape of its orbit around the Sun vary slowly over tens of thousands of years.
This changes climate by changing the seasonal and latitudinal distribution of incoming solar energy at Earth's surface. Climate change feedbackClimate sensitivityand Arctic amplification The dark ocean surface reflects only 6 percent of incoming solar radiation, whereas sea ice reflects 50 to 70 percent.
Positive feedbacks increase the response of the climate system to an initial forcing, while negative feedbacks reduce it.
Other factors being equal, a higher climate sensitivity means that more warming will occur for a given increase in greenhouse gas forcing.
More research is needed to understand the role of clouds  and carbon cycle feedbacks in climate projections. Another study conducted by Harvard researchers suggests that increased water vapor injected into the stratospheredue to rising temperatures, increases ozone depletionsubsequently raising the odds of skin cancer and damaging crops.
Projected change in annual mean surface air temperature from the late 20th century to the middle 21st century, based on a medium emissions scenario SRES A1B. Global climate model A climate model is a representation of the physical, chemical and biological processes that affect the climate system.
Results from models can also vary due to different greenhouse gas inputs and the model's climate sensitivity. For example, the uncertainty in IPCC's projections is caused by 1 the use of multiple models  with differing sensitivity to greenhouse gas concentrations,  2 the use of differing estimates of humanity's future greenhouse gas emissions,  3 any additional emissions from climate feedbacks that were not included in the models IPCC used to prepare its report, i.
Instead the models predict how greenhouse gases will interact with radiative transfer and other physical processes. Warming or cooling is thus a result, not an assumption, of the models. Improving the models' representation of clouds is therefore an important topic in current research.Understanding Global Warming Potentials Greenhouse gases (GHGs) warm the Earth by absorbing energy and slowing the rate at which the energy escapes to space; they act like a blanket insulating the Earth.
Archer's Global Warming: Understanding the Forecast2nd Edition, is the first real text to present thescience and policy surrounding climate change at the right attheheels.comanying videos, simulations and instructional support makes iteasier to build a syllabus to .
Global Warming: The Imminent Crisis That Never Arrives, But Always Needs MORE Money From YOU 78 points • 4 comments • submitted 19 days ago by SuperCharged to r/climateskeptics The Arctic was supposed to be ice-free, hurricanes were going to be more frequent and more deadly, and sea levels should be rising alarmingly.
An overview of the causes and consequences of the global financial crisis that hit the world in , last updated September 30, Global Issues.
(global warming and other problems) Cultural (intolerance, clash of religions, Western cultural dominance) Flawed assumptions about the underlying economic systems contributed to this. Research that estimates the relative impacts of proximate human causes of global change on particular environmental changes of concern, specifying the uncertainty of the estimates, is essential for understanding the human dimensions of global change.
In the picture, a polar bear becomes homeless in a dirty street due to the loss of habitat caused by global warming. In fact, in addition to polar bears, many other species, including human beings, are also suffering from the effects of global warming. In the past few decades, the devastati.