Claim: The main reason behind this mid-century cooling was global dimming due to anthropogenic sulfate aerosol emissions.

Relevance (1 = gold evidence, 0 = mined hard negative): 1
Passage: Although the temperature drops foreseen by this mechanism have now been discarded in light of better theory and the observed warming, aerosols are thought to have contributed a cooling tendency (outweighed by increases in greenhouse gases) and also have contributed to "Global Dimming."

Relevance (1 = gold evidence, 0 = mined hard negative): 1
Passage: While most of the earth has warmed, the regions that are downwind from major sources of air pollution (specifically sulfur dioxide emissions) have generally cooled.

Relevance (1 = gold evidence, 0 = mined hard negative): 1
Passage: From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed, a phenomenon popularly known as global dimming, typically attributed to aerosols from biofuel and fossil fuel burning.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: In the latter half of the century, we find that anthropogenic increases in greenhouses gases are largely responsible for the observed warming, balanced by some cooling due to anthropogenic sulphate aerosols, with no evidence for significant solar effects.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: The cooling period is reproduced by current (1999 on) global climate models (GCMs) that include the physical effects of sulfate aerosols, and there is now general agreement that aerosol effects were the dominant cause of the mid-20th century cooling.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: GHG emissions due to anthropogenic (human) activity are the dominant cause of observed global warming (climate change) since the mid-20th century.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: Anthropogenic particulates such as sulfate aerosols in the atmosphere reduce the direct irradiance and reflectance (albedo) of the Earth's surface.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: Modern climate models addressing the attribution of recent climate change take into account sulfate forcing, which appears to account (at least partly) for the slight drop in global temperature in the middle of the 20th century.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: Most of the observed warming occurred in two periods: around 1900 to around 1940 and around 1970 onwards; the cooling/plateau from 1940 to 1970 has been mostly attributed to sulphate aerosol.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: Cumulative anthropogenic (i.e., human-emitted) emissions of CO 2 from fossil fuel use are a major cause of global warming, and give some indication of which countries have contributed most to human-induced climate change.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: The 2007 Fourth Assessment Report compiled by the IPCC (AR4) noted that "changes in atmospheric concentrations of greenhouse gases and aerosols, land cover and solar radiation alter the energy balance of the climate system", and concluded that "increases in anthropogenic greenhouse gas concentrations is very likely to have caused most of the increases in global average temperatures since the mid-20th century".