Mummified leaves give researchers climate change clue

“Mummified” leaves from a 23-million-year-old forest have given scientists the chance to peek into the future and the possible effects of climate change.

Ancient fossil leaves preserved in what was once a New Zealand lake bed show how high levels of carbon spurred ancient “global greening”.

The new findings add to our current understanding of global warming and how plant life might shift within decades when CO2 levels could closely mirror those of the distant past.

In the study, scientists salvaged the leaves from the lake bed located in a small, long-extinct volcanic crater now on a farm near Dunedin in southern New Zealand.

The so-called “carbon fertilisation effect” has vast implications, according to the researchers. Lab and field experiments have shown that when CO2 levels rise, many plants increase their rate of photosynthesis because they can remove carbon from the air better and save water while doing so.

Previous research based on Nasa satellite data shows a “global greening” effect mainly due to rising levels of manmade CO2 over recent decades.

Dr Tammo Reichgelt, an assistant professor of geosciences at the University of Connecticut, said: “This might seem like good news but the reality is more complex.

“Increased CO2 absorption will not come close to compensating for what humans are pouring into the air. How it plays out is anyone’s guess. It’s another layer of stress for plants.”