The change in the seasonal cycle proves the involvement of humans in driving climate change

One of the causes that climate scientists have been able to decide with certainty that humans are responsible for modern warming is that they have more work than simple climate records. There are many places where a human source can be seen only if you know how to dust off for fingerprints. For example, while the lower atmosphere is warming, the stratosphere is surprisingly cool. That's what you think when greenhouse gases – other than the Sun – are the real reason for global warming.

A new study supervised by Ben Santer of the Lawrence Livermore National Laboratory for fingerprints in a new region: the seasonal cycle of temperatures. The ideal equipment to inspect it is the global temperature survey generated by the satellites, which began their search in the year 1979. This means that they do not go back until the next registrations meteorological stations, but the data are now long enough to prove useful for studies like this

Hot and Cold

While everyone works with the same satellites, many different groups really work with sets independent satellite temperature data. This is because the calculations are far from effortless, and the large number of work goes into all the important organization for advertising temperature maps. As a result, the different sets of data do not always come together ideally – or with those that are examined with older versions of their processing algorithm. Thus, in this study, the researchers used the two most recent versions of three different data files.

Further reading

Each data file follows different layers of which our atmosphere is composed. A record traces the lower troposphere – the first 10 kilometers above the surface of the Earth. Although this is the closest thing to the surface temperatures in which we live, it is also the most difficult to obtain a correct measurement. The best recording centers present in the mid-troposphere, a little higher.

By plotting the contrast between the coldest months of winter and the hottest summer months, the extent of the annual cycle of the seasons.

If you calculate the mean latitudinal mean of the northern hemisphere, there is a seasonal temperature change comparable to that of the southern hemisphere, because there is much more land ( which heats up and cools to significant extremes in comparison to what the ocean does). But since 1979, in general, this seasonal cycle has developed, even more so in the northern hemisphere, because of the increase of the temperature in summer in the atmosphere compared to the winter temperatures [19659009]. coherent. On the other hand, near the poles, satellites display a reduction in the seasonal temperature swing.

There is an exciting deviation that does not describe this model: the University of Alabama dataset at Huntsville, led by Roy Spencer and John Christy (two of the few scientists opposed to the voice that rejects or minimizes climate change of human origin). This dataset looks totally different in Antarctica. In fact, the strangeness in the Huntsville data only appears in its latest updated version and seems to examine a difficulty managing change between first and second generation satellites. There is a history of managers of other major satellite datasets that have found errors in the Huntsville algorithm, and this seems to relate to another instance.

Models and Reality

So, what is the meaning of these modified seasonal patterns? To answer this question, Santer and the other researchers receive help from a duplicate collection of vital climate models. This includes extensive simulations of a constant climate (pre-industrial revolution), as well as simulations of global warming generated by humans by 2016. This allowed the research to examine climate models prediction models for a warming world, as well as the researchers have discovered that models almost see this perfect seasonal pattern – significant seasonal fluctuations in mid-latitudes (specifically for the northern hemisphere), a small difference In the region. tropics, and minor oscillations in Antarctica. The models also accurately predict a slightly small seasonal cycle around India and Southeast Asia, which departs from the general trend of mid-latitudes.

The only contradiction is in the Arctic. t compared to the prediction of an average model. Nearly a third of the models show a decrease, but the rest does not show. The models have normally underestimated the reduction of ice in the Arctic Sea, and there is one possibility that is the key here, as the loss of sea ice is a major factor in the change in the seasonal cycle.

That's Us, Version 857

To examine how sharp the observed satellite changes point to the warming of human origin, the researchers used a signal-to-noise badysis. They use the relevance of the industrial pre-revolution to predict the magnitude of natural variability, badysis has shown that seasonal patterns observed in the average troposphere have emerged distinctly above noise. This makes it an understandable demonstration of the models provided by the models. It is clearer than the change in global average temperatures, in reality, because seasonal trends over entire bands of latitude would not differ much in the presence of much in a stable climate.

While they were there, the researchers repeated these badyzes for a clearer badessment of climate change: the average annual temperatures, examined at various locations around the world. They write: "We find here that, for the annual average [mid-troposphere temperatures] the estimated [signal-to-noise] ratios exceed 4.4 for temperature changes over the 38 years of the satellite record. This translates into a probability of about 5 in 1 million to obtain annual average ratios [signal-to-noise] by natural variability alone. "

In general, they deduce:" The best explanation of these results is that fundamental physics and fundamental physical mechanisms are driving large-scale changes in [seasonal patterns]. For tropospheric temperature, a signal caused by man is now evident in the seasonal cycle itself. "

Which is also a logic of more scientists can be sure that humans are making a change of climate.