Anyone who claims there is no global warming seriously does not know what they are talking about. There is abundant evidence for it in many places. Warming of the seas, rising sea levels, melting of the polar ice caps, melting glaciers, satellite imagery showing the melting that has occurred from trapped greenhouse gases, spring coming on average three weeks earlier, drying rivers, vastly increased levels of CO2 in the atmosphere since the start of fossil fuel burning, bleaching of coral reefs, warming of the troposphere, and more frequent and severe el ninos.
Part of the warming is caused by one big loop. Fossil fuels have warmed the lower layer of the atmosphere causing melting ice which reduces the albedo effect (the amount of light reflected back into space),and warms the earth even more. Another factor has been the large scale reduction of forests which absorb CO2. Less forests means less CO2 absorbed by plants-thereby causing more to be released into the atmosphere warming the earth even more.
Even if we totally stopped all C02 emissions as of today..the amount of CO2 released into the atmosphere already will continue to warm the earth long after we're gone. These emissions and severe changes in C02 composition since the time of the industrial revolution have been observed and noted. They are not up for debate.
The evidence is all around. Nothing so great as the power of denial.