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The connection between pollen and the rise in global temperatures

"Projections for future climate change are more likely to produce more trustworthy predictions if they include changes in vegetation.”

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By Tom Campbell via SWNS

Plants could shed fresh light on the rise in global temperatures over the past 10,000 years, scientists found after studying pollen.

Wide shot of a beekeeper holding the beehive frame filled with honey against the sunlight in the field full of flowers
(Juice Flair/Shutterstock)

Climate models that examined carbon dioxide (CO2) levels or ice cover could be missing a vital piece of the puzzle.

Most of these models show global temperatures rising consistently over time since the last ice age.

But evidence suggests there was a peak in mercury somewhere between 6,000 and 9,000 years ago.

Now scientists from the University of Michigan have set the record straight by looking at vegetation changes.

Study author Dr. Alexander Thompson said: “Pollen records suggest a large expansion of vegetation during that time.

“But previous models only show a limited amount of vegetation growth.

“So, even though some of these other simulations have included dynamic vegetation, it wasn’t nearly enough of a vegetation shift to account for what the pollen records suggest.”

A geological period known as the Holocene began after the last ice age ended around 10,000 years ago and plants blossomed.

The Sahara Desert in Africa grew greener than it is today, becoming more of a grassland than desert.

Other vegetation like the coniferous and deciduous forests in the mid-latitudes and the Arctic also thrived.

The researchers used a climate model dubbed the Community Earth System Model (CESM), which is regarded as one of the best, to see what effect this green growth had on global temperatures.

They carried out experiments using pollen records to simulate changes in vegetation that had not been taken into account before.

It revealed that warmer temperatures had brought an abundance of plants before rising even further.

The flowers of the pussy willow with pollen. Spring flowering plants. Allergy to pollen.
Pussy Willow flowers with pollen. (Greens and Blues/Shutterstock)

Dr. Thompson said: “Expanded vegetation during the Holocene warmed the globe by as much as 1.5 degrees Fahrenheit.

“Our new simulations align closely with paleoclimate proxies.

“So this is exciting that we can point to Northern Hemisphere vegetation as one potential factor that allows us to resolve the controversial Holocene temperature conundrum.”

Understanding global temperature changes throughout the Holocene could shed light on human development, because human agriculture and civilization took place during this period in history.

Dr. Thompson, who conducted the research as a graduate student at the University of Michigan said: “Overall, our study emphasizes that accounting for vegetation change is critical.

“Projections for future climate change are more likely to produce more trustworthy predictions if they include changes in vegetation.”

The findings were published in the journal Science Advances.

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