With the worldwide industrialization process, more and more carbon dioxide is discharged into the atmosphere, resulting in the "greenhouse effect", and the global temperature is gradually rising, which has triggered a series of climate changes, including the shortening of the global ice age and the rise of sea level. This inference has been recognized by more and more scientists. So, did the "greenhouse effect" only happen in recent decades? Has it ever appeared in geological history? Some geologists believe that large-scale volcanic eruptions in geological history will also cause a corresponding increase in the content of carbon dioxide in the atmosphere. Will there be other reasons? Not long ago, a new discovery in the North American continent once again aroused people's discussion on this topic.

A doctor from the Department of Geology of a university in Colorado, USA, accidentally discovered a strange fossil in the local Jurassic strata when completing the field investigation of his doctoral thesis. After identification by several scientists, he thought it was a termite nest fossil. The doctor outlined hundreds of discovery points of Jurassic termite nest fossils on the map. This gives people a detailed picture of the strange ecosystem about1.500 million years ago.

Because termites nest fossils are mostly associated with forest and tufted plant fossils, they are relatively easy to find. Later, the expert team explored everywhere and soon found a large number of termite nest fossils in Jurassic strata in Utah, New Mexico and southwest Colorado. This new discovery greatly compensates for the fossil record of termites, which is similar to the Jurassic termite nest fossils recently discovered in northern Australia and southern Africa.

Prior to this, the earliest fossil evidence of termite nests was fossil entities from England and Spain, which occurred in the middle Cretaceous about 1. 1 100 million years ago. 1994, with the assistance of the US Federal Geological Survey, after several months of field work, this expert group found more ancient termite nest fossils in some famous national forest parks in the United States, which were the products of the Middle Triassic about 200 million years ago. This is the oldest evidence of social insects found so far. After detailed statistics and comparison, it is found that the number of termites in Jurassic is much higher than that in Triassic.

Modern termites like to nest in xylem and roots of dead trees. Once the trees die, termites will build thousands of interconnected "art palaces" inside them, just like the modern highway network. Obviously, the Jurassic termite nests were preserved in the roots of petrified bushes and trees, which is very similar to the living habits of modern termites. Some nests of termite fossils wrap the roots of plants, which are the size of basketball and are oval or semicircular.

Termites, like ants, bees and wasps, live in large groups with a clear division of labor. In order to protect their "art palace", these insects must be highly socialized. They must build and maintain their nests, resist invaders and predators, and protect their offspring.

At present, fossil data show that termites evolved from a cockroach that eats wood. In order to dissolve and digest the wood they eat, the bacteria in termites' stomachs will produce a lot of methane, which will be discharged into the atmosphere as a by-product. According to the calculation of some scientists in North America, termites living all over the world can release about 40 million tons of methane into the atmosphere every year, which is 1/2 of the total methane released by animal life on earth (human beings are also the largest methane producers in the world) and four times that released by the ocean.

Like carbon dioxide, methane is also an important substance that produces the "greenhouse effect". American scientists believe that termites have been releasing methane into the atmosphere since Triassic, so they will definitely have an impact on the global carbon cycle, at least this impact will have an impact on the Cretaceous climate, making it wetter and closer to the equator than Jurassic. Of course, whether this is a scientific inference or a "fantasy" remains to be further studied.