The impact of global warming can already be seen in the habitats around us, according to a study that saw scientists run heaters outside for 23 years.

Ecologists monitored the changes that took place in meadows in the Rocky Mountains and compared them to plots others that were artificially heated to simulate global warming.

After more than two decades, they found that the unheated meadow plot as are now starting to resemble those that had changed quickly as a result of the artificial heating.

The researchers studied meadows at the Rocky Mountain Biological Laboratory in Gothic, Colorado (above)

The vegetation in the meadows shifted to become more woody while the soil became poorer quality.

STORMS WILL GET BIGGER BUT NOT MORE COMMON AS EARTH WARMS For years, scientists have predicted that as global warming heats the Earth, the number of storms will increase. But recent research suggests that rather than increasing in number, these storms will increase in intensity - meaning the same number of storms will occur, but they'll be stronger. The physicists behind the study said that this is because global warming will directly affect how the atmosphere circulates air mass, heat and water using what has been dubbed 'Earth's heat engine.' Researchers from the University of Toronto used computer models to simulate how Earth and its atmosphere will change between 1982 to 2098. As a result of climate change, they predicted the atmosphere is expected to use more energy to cycle water around the heat engine. This is because an increase in water vapour will make the process less efficient. However, the atmosphere still needs to get rid of the precipitation it collects, but because circulation is affected, it has to do this in fewer, more intense storms. Advertisement

The researchers say these changes resemble those that are taking place in landscapes around the world due to global warming.

However, to achieve their results, the experiment itself may have contributed to global warming.

The scientists set up infrared heaters over the five meadow plots measuring 30 square metres (322 square feet).

Left to run day and night, the heaters burned through more than 128,462 kilowatt hours of electricity.

This means that the heaters produced around 78 tons of carbon dioxide during the life-time of the experiment - roughly the equivalent of driving an average family car 87 times around the world.

By comparison, however, the average energy usage per capita in the US is 9,500 kilowatt hours a year.

This means over the course of the same 23 year project, the average US citizen would used almost twice as much energy as was used to conduct the experiments - 218,500 kilowatt hours.

Professor John Harte, an ecosystems scientist at the University of California, Berkeley, who led the study, said the round the clock heating was necessary to understand what the cause the changes in the unheated plots were.

He said: 'The annual energy usage each year of the experiment is roughly comparable to the annual energy consumption by an average US resident.

'At a personal level I feel comfortable doing this because 15 years ago I put solar panels on my roof and I walk the two km to my university and back each day, never driving.

'Finally, of course, I justify it because the knowledge obtained provides considerable insight into the nature of the threat that the world faces.'

The research, which is published in the journal Global Change Biology, was conducted at the Rocky Mountain Biologial Laboratory in Gothic, Colorado.

It showed that in the past decade the unheated 'ambient' meadow plots started to change in the past decade.

The heaters (seen above) caused snow to melt earlier but snow melt in unheated plots has begun to catch up

These graphs show the changes in non-woody plants (top) and woody shrubs (bottom) in the heated and unheated meadows over 23 years, revealing how climate change has altered the vegetation in unheated plots

Snow on these plots started to melt earlier while the growth and flowering of non-woody plants decreased.

The researchers said woody shrubs increased on the plots and the levels of carbon in the soil also declined.

This, they said, matched what had been observed in the meadow plots that had been heated, but at a far slower rate.

Professor Harte and his colleagues Scott Saleska from the University of Arizona, Tucson, and Charlotte Levy, from Cornell University in Ithaca, said what was happening on these meadows matched what was occurring in the wider environment.

Writing in the journal, they said: 'This allows us to infer that climate change is the cause of the observed shifts in ambient vegetation and soil carbon and that the vegetation responses mediate the observed changes in soil carbon.

The heaters were left running day and night above five of the meadows in the Rocky Mountains (as shown above) to provide a way of attributing changes that occurred naturally in the unheated areas of the test site

This graph shows how carbon in the soil of unheated plots is starting to catch up with those in heated plots

'The trends we observed over the last decade in the ambient plots are consistent with broader scale observations throughout western North America that indicate a reduction in carbon uptake due to recent drought as well as an increase in shrub production.'

Professor Harte said that the experiments could also provide some clues about what the future could hold as the climate warms further.

He told Mail Online: 'The heated plots have not yet achieved a new steady stat.

'Forb biomass (non-woody plants) is continuing to deline, shrub biomass is increasing.

'Soil carbon is slowly increasing as well and the heated plot snowmelt dates continue to come earlier because they are seeing not just the heaters but also the ambient warming trend.'

The heated plots also tend to be 10-20 per cent dryer during the growing season and are snow free on avearge two weeks earlier.

The heaters made the top 15 cm of soil around two degrees warmer than the surrounding area.

Professor Harte added: 'With only control plot observations, it is very difficult to know what causes the observed trends.