April
2007
Cool forests0
Links to free teaching resources for the forests warming story
Teaching resources (UK US) designed specifically for this story at www.realscience.org.uk
“Is human activity bringing about alarming global warming and related catastrophes? Or is such thinking a myth brought about by flawed or incomplete science?” Detailed lesson and resources from PBS.
“Changes to Earth’s global climate have had and will have major consequences for life on Earth. Using evidence preserved in ice for tens of thousands of years, scientists are searching for an understanding of the history of Earth’s climate changes in order to predict what the future holds for life on the planet. In this lesson, students learn about ways in which we study past climate change, and reflect on the present condition of Earth’s climate.” Detailed lesson and resources from Teachers’ Domain (simple registration required).
“Climate changes have occurred throughout Earth’s history, with dramatic consequences to the organisms that live there. Although some climate changes are a part of Earth’s natural cycles, others are the by-product of human activity… In this lesson, students conduct an experiment to learn about CO2 levels in different gases. Then they reflect on CO2 production on a global scale. They also look at evidence of global warming in our environment, and consider their own role.”
“In the past few years several attempts have been made to assess changes in the Earth’s planetary albedo, and claims of global dimming and more recently brightening have been debated in journal articles and blogs.”
“This site gives students an opportunity to explore storm clouds and climate change through the use of NASA climate research data obtained through satellite imaging. The challenge is to investigate actual scientific research data on clouds and storms, and make the resulting observations and interpretations available to NASA research scientists for review.”
Climate change for kids.
“Inquiry-based classroom activity which explores the impact of climate change and variability on forests… The scenario invites students to examine higher level issues of climate variability and change, by creating a practical, scientifically-sound model to address specific points of a localised situation.”
This applet lets students explore how emissivity, albedo and solar output affect temperature throughout the atmosphere. There are controls for adjusting atmospheric emissivity, planetary albedo, and the solar constant.
The story:
Uncool trees
Planting new trees in certain parts of the planet may warm the Earth, according to a new study.
The research was led by Govindasamy Bala. He is an atmospheric scientist at Lawrence Livermore National Laboratory. It appears in the April 9-13 online edition of the Proceedings of the National Academy of Sciences.
Planting and preserving forests in the tropics, on the other hand, is likely to slow global warming.
The new study looks at the effects of large-scale deforestation on climate and the carbon cycle. It uses an interactive, 3-dimensional, climate-carbon model.
The model showed that more trees in mid-latitudes, like the United States and most of Europe, would create slight benefits. But extra trees in the forests of Canada, Scandinavia and Siberia could make things worse.
Forests affect climate in three different ways. They absorb the greenhouse gas carbon dioxide from the atmosphere. This helps stop the planet from warming. They evaporate water to the atmosphere and increase cloudiness. This helps keep the planet cool too.
But the third effect arises because forests are dark and absorb sunlight. This is called the albedo effect. Unlike the other two this helps warm the Earth.
The new study shows that only tropical forests are strongly helpful in helping slow global warming, Bala said.
It is a win-win situation in the tropics, he added. Trees there absorb carbon dioxide. They also create clouds that cool the planet. “In other locations, the warming from the albedo effect either cancels or exceeds the net cooling from the other two effects.”
Other researchers from the Carnegie Institution, Stanford and Université Montpellier II, France also contributed to the report.
The authors state firmly that cutting down trees outside the tropics should not be seen as a way to lessen climate change.
Preserving ecosystems is one of the main goals of preventing global warming, said Ken Caldeira. He is at the Carnegie Institution and is a co-author of this report. “The destruction of ecosystems to prevent global warming would be a counterproductive and perverse strategy.
“Apart from their role in altering the planet’s climate, forests are valuable in many other aspects,” Bala said.
Forests provide natural habitat to plants and animals. They preserve biodiversity. They produce valuable timber and firewood. They protect watersheds and help prevent oceans turning acid.
Broad goals should be pursued when planning responses to global challenges, Caldeira said. “It is important to avoid narrow criteria that may lead to environmentally harmful consequences.”
