African and Indian monsoon systems weakened, and rain that should have fallen on hot soils dropped as more snow over Europe. Between 18, Alpine glaciers – now in alarming retreat – actually advanced. Mt Tambora in what is now Indonesia put so much ash into the stratosphere to screen sunlight and drop temperatures that 1816 became known as the Year without a Summer.īut there were also four other eruptions.
The Little Ice Age began in Europe with no obvious trigger, but it was certainly reinforced and extended by more violent than usual volcanic activity in the tropics between 18. The peak periods of pre-industrial warm and cold periods occurred at different times in different places.”Īnd his Bern colleague Stefan Brönnimann clears up another point in a related study in the pages of Nature Geoscience. “It’s true that during the Little Ice Age it was generally colder across the whole world,” says Raphel Neukom of the University of Bern in Switzerland, and first author, “but not everywhere at the same time. They were random fluctuations within the climate system, and even changes in solar activity or volcanic surges could not affect all of the planet at any one time. There have been changes in modern human history, but none of them global and synchronous (happening at the same time). But it matters, because the Nature study clarifies a point of possible confusion.
Climate scientists, conservationists, glaciologists, marine biologists, geologists and economists all know that climate change is happening, and that it is happening as a consequence of accelerated human activity over the last two centuries.īut from the start, there have always been gnawing questions: hasn’t the climate always changed? If global temperatures rose between 700 AD and 1400 AD, and then fell again, is what is happening now not part of some similar long-term cycle? And until now, that has remained without a confident, categorical answer. Research like this is a tidying-up operation. “This paper should finally stop climate change deniers claiming that the recent observed coherent global warming is part of a natural climate cycle” The finding is part of a sustained examination of global climate history, based not just on written and pictorial records but also studies of ancient lake sediments, ice cores, tree rings and other proxy evidence assembled by an international partnership called the Past Global Changes Consortium. The present sustained, ubiquitous warming is unique in that it can be coupled directly with the Industrial Revolution, the clearing of the forests, population growth and profligate use of fossil fuels.