Extreme weather has gripped much of the US recently and thousands of heat records have been broken. At least 46 deaths have been linked to the July heat wave alone.
A study released this week shows that the last 12 months have been the warmest on record for the US mainland. And these numbers do not even include July's high temperatures.
"There's a certain randomness to weather, the precise temperature we get on any given day is going to depend on the vagaries of the weather. But what we're seeing right now is the clear loading of the weather dice towards these more extreme temperatures .... If you look at the past decade, we have seen all time records for warmth in the US broken at twice the rate we'd expect from chance alone."
- Michael Mann, a climate scientist
In late June, a violent weather system left more than a dozen people dead and millions without power for days across several states.
Most of the country is suffering from moderate to extreme drought, creating conditions ideal for raging wildfires.
So far this year, more than 850,000 hectares have been engulfed in flames across the US.
But scientists have been reluctant to directly link the wild weather to climate change, although they say it is consistent with global warming.
However, a study by the National Oceanic and Atmospheric Administration in the US and the UK's Met Office, released on Tuesday, for the first time did directly link some recent weather events to climate change, including last year's heat waves in Texas and the UK.
It says five of six extreme weather events in 2011 were at least partly caused by climate change.
Last year's record heat wave in Texas was about 20 times more likely to have happened due to climate change.
The study said there was evidence that the drought which struck East Africa last summer resulting in a famine was at least partially caused by climate change altering sea temperatures.
"We understand of course there is natural variability, some summers are harder than others and there are a lot of causes for wildfire and drought ... but when you say ... we have just now finished the hottest year on record in the United States, 3.2 degrees higher than the 100-year average ... when that's the background against which all these weather events are unfolding, it's important that we connect the dots on where we're headed and what we need to do to address climate change, mitigate its impacts and prepare for it to adapt to its consequences."
- Bob Deans, associate director of communications for the Natural Resources Defense Council
And last year's record warm November in the UK was at least 60 times more likely to have happened due to climate change than natural variations in weather systems.
The group Media Matters analysed coverage of the western wildfires across mainstream television and print outlets between April 1 and June 30, showing there were 258 segments focusing on US wildfires on television but only four mentioned climate change as a possible factor.
And there were 135 print articles - of which only eight mentioned global warming.
So only three per cent of stories on the wildfires even raised the question of climate change as a factor, despite the fact that multiple studies have determined that climate conditions influence the development of wildfires.
The United States Global Change research programme issued a report in 2009 that found that global warming was unequivocal.
The government report also found that it is primarily human induced. It warns that climate change will put stress on water resources, crop and livestock production and put highly developed coastal areas at risk.
It also found that threats to human health will increase – these threats include heat stress and poor water quality as well as threats from water and insect-borne diseases.
The report found that climate change is already underway in the US and these changes are projected to grow. It also found that heat is a leading cause of death in the US. Between 1970 and 2004, nearly 20 per cent of all hazard-related deaths in the country were caused by heat and drought.
So is this what global warming looks like?
To discuss this, Inside Story Americas, with presenter Shihab Rattansi, is joined by guests: Michael Mann, a professor and director of Penn State's Earth System Science Center and author of The Hockey Stick and the Climate Wars: Dispatches from the Front Lines; Bob Deans, the associate director of Communications for the Natural Resources
Defense Council; and Heidi Cullen, the vice president for external communications and the chief climatologist for Climate Central.
"I think it is really important to keep in mind that there is a number of different factors that go into play in the creation of any given weather event. And we can do attribution studies, climate scientists do this. In fact we have studied for example the European heat wave of 2003 and what we were able to do after the fact was basically to say
that human actions, the burning of fossil fuels and other actions, basically doubled or possibly quadrupled the likelihood of that heat wave .... Our job is to make people think about the long-term risks that are building up within our climate system right now. So when we keep in mind the time lags inherent within our climate system, we are basically loading the dice for more and more of these extremes and it really puts us in harm's way."
Heidi Cullen, the vice president for external communications and the chief climatologist for Climate Central
- International energy agency: 34.7bn tonnes of CO2 released daily in 2011
- International energy agency: global CO2 emissions hit record high in 2011
- Ocean levels have risen by about 20cm in the last century
- Average temperature has risen 0.75 degrees Celsius in 100 years
- The 20th century's last two decades were the hottest in 400 years
- In 2012, nearly 850,000 hectares have burned in wildfires
- Arctic Circle could be ice-free during summer in next ten years
- World Health Organisation: 140,000 deaths each year are caused by global warming
- The US is responsible for nearly 25 per cent of the CO2 emissions worldwide