Humans have been warming the climate for nearly 200 years, scientists say

This story originally appeared on the Guardian and is part of the Climate Desk collaboration.

Continents and oceans in the northern hemisphere began to warm with industrial-era fossil fuel emissions nearly 200 years ago, pushing back the origins of human-induced climate change to the mid-19th century.

The first signs of warming from the rise in greenhouse gases which came hand-in-hand with the Industrial Revolution appear as early as 1830 in the tropical oceans and the Arctic, meaning that climate change witnessed today began about 180 years ago.

Researchers in Australia found evidence for the early onset of warming after trawling through 500 years of data on tree rings, corals and ice cores that together form a natural archive of Earth’s historical temperatures.

Much of what is known about Earth’s climate history is based on instruments that have monitored temperatures from the 1880s onwards. But while these capture the changing conditions seen in the 20th century, they miss the start of the warming trend.

“A lot is known about the climate record for the time when we have instrumental records,” said Nerilie Abram, a climate scientist at the Australian National University. “We wanted to look at whether these records give us the full picture.”

Pooling the data, the scientists found that temperatures in the tropical oceans and in the air above northern hemisphere land-masses began to rise above natural variations in the 1830s, just as greenhouse gas emissions edged upwards.

The scientists first thought that they were seeing the climate rebound after a period of natural cooling brought on by particles thrown high into the atmosphere from volcanic eruptions. But climate simulations showed that the warming they observed could be explained purely by the small rise in greenhouse gas emissions.

“The changes in greenhouse gases in the 19th century were small compared with the fairly rapid changes we see now, so seeing the climate respond this way was a surprise,” said Abram.

Tommy Monk wrote:Not what the IPCC say and not what is widely reported either...


http://www.nationalreview.com/article/427823/paris-climate-conference-no-warming



And wolfboy cones in with irrelevant waffle once more...


I didn't make up the name 'mini ice age'... or 'little ice age' as it is also known...

nicko wrote:For fcuks sake,     have I got to sell my Range Rover or not?

Tommy Monk wrote:


Ben.. you are posting waffle again because if temps have only risen 0.85 degrees since 1880, and only 0.06 degrees over the last 20 years, as is widely confirmed by ipcc and other reputable sources... then it is impossible for all those years shown in your picture to be so much higher than this total amount when compared to the average temp over the whole of 20th century as it claimed...

Sceptics who still doubt anthropogenic climate change have now been stripped of one of their last-ditch arguments: It is true that there has been a warming hiatus and that the surface of the earth has warmed up much less rapidly since the turn of the millennium than all the relevant climate models had predicted. However, the gap between the calculated and measured warming is not due to systematic errors of the models, as the sceptics had suspected, but because there are always random fluctuations in the Earth's climate. Recently, Jochem Marotzke, Director at the Max Planck Institute for Meteorology in Hamburg, and Piers M. Forster, a professor at the University of Leeds in the UK, have impressively demonstrated this by means of a comprehensive statistical analysis. They also clearly showed that the models do not generally overestimate man-made climate change. Global warming is therefore highly likely to reach critical proportions by the end of the century - if the global community does not finally get to grips with the problem.

Climate is subject to chance and chaos - which makes life difficult for climate researchers. No wonder that these two unpredictable climate factors lie at the root of a mystery that has baffled scientists since the start of the 21st century. Since then, the temperature of the Earth's surface has increased by only around 0.06 degrees Celsius - much less than had been predicted by all 114 model simulations considered in the climate report by the IPCC. Jochem Marotzke and Piers M. Forster have now explained the warming pause in terms of random fluctuations arising from chaotic processes in the climate system. Even more importantly for the two researchers and their colleagues around the world: they did not find any conceptual errors in the models. Most notably, the models do not generally react too sensitively to increases in atmospheric carbon dioxide.

"The claim that climate models systematically overestimate global warming caused by rising greenhouse gas concentrations is wrong," says Jochem Marotzke. Climate sceptics often make precisely this claim, citing the warming pause as evidence. Yet they cannot deny that nine of the ten warmest years since systematic climate observations began have occurred in the new millennium and that global warming has slowed at a very high level. The sceptics also ignore the fact that ocean temperatures continue to rise as rapidly as many models have predicted.
"On the whole, the simulated trends agreed well with the observations"

To explain the puzzling discrepancy between model simulations and observations, Jochem Marotzke and Piers M. Forster proceeded in two steps. First, they compared simulated and observed temperature trends over all 15-year periods since the start of the 20th century. For each year between 1900 and 2012 they considered the temperature trend that each of the 114 available models predicted for the subsequent 15 years. They then compared the results with measurements of how the temperature actually rose or fell. By simulating the average global temperature and other climatic variables of the past and comparing the results with observations, climatologists are able to check the reliability of their models. If the simulations prove more or less accurate in this respect, they can also provide useful predictions for the future.

eddie wrote:Tommy, you're going to make Ben and wolfie's head explode.

eddie wrote:Tommy, you're going to make Ben and wolfie's head explode.

Tommy Monk wrote:

eddie wrote:Tommy, you're going to make Ben and wolfie's head explode.

Basic maths eddie...