Satellite data is helping us understand our changing planet

Given the interest in carbon capture in the broader fight against climate change, a recent paper tallied up all the carbon held by the plants and soils covering Canada’s vast landscapes. It was a herculean task, given that Canada has some nine million square kilometres of land. 

Monitoring all those trees, plants and soils over such a large area only recently became possible because of advances in a technology called lidar (or light detection and ranging), which could help Canada protect those important carbon stores and combat global warming.

Lidar is a laser technology that can be used to build a three-dimensional picture of the landscape. The carbon study used data from lidar mounted on a satellite orbiting the Earth, shooting laser beams down at the surface and measuring the speed at which those beams are bouncing back. 

This was then used to calculate the height of plants and trees all over Canada, making it possible to estimate the carbon stored in those ecosystems.

Lidar has been around since the 1960s, but the level of detail in the carbon study was not available before.

“This is definitely a huge jump technologically,” said Valerie Casasanto, the outreach co-ordinator at NASA’s ICESat-2 satellite project, which launched in 2018. Data from the satellite, whose sole instrument is a lidar laser, was used in the carbon study. 

“[The satellite’s lidar] gets a much, much higher precision. You can measure within about four millimetres of difference and changes.”

The primary scientific objective of ICESat-2 is to measure the changing cryosphere — including continental ice sheets in Greenland and Antarctica, glaciers, ice caps and sea ice around the poles. But Casasanto says as the satellite collects reams of richly detailed data from around the planet, researchers have found their own uses for it.

That includes more than 100 studies and counting, including one that looked at the migratory patterns of penguins in the Antarctic Peninsula. 

Previously, satellite imagery could only measure sea ice during sunlit months in the region, but ICESat-2’s laser beams work in the darkness as well, allowing scientists to figure out where there’s sea ice and open water in the winter.

Lidar is also turning up in other climate-related applications. A groundbreaking study on methane emissions in B.C. used lidar mounted on an airplane to “see” plumes of the gas. Methane, the main component of natural gas, leaks from oil and gas production sites but is difficult to detect because it is colourless and odourless. 

Ferreting out such leaks is key because methane is 70 times more potent than carbon dioxide as a greenhouse gas and a key target in the fight against climate change.

Data from ICESat-2 is used widely because it is made freely available. The project is fully funded by the U.S. governmen, and its planned lifespan was three years.

It is now about two months beyond that. Casasanto says the data mission could run for seven years based on the fuel onboard and possibly longer with some adjustments — providing important information on our changing planet as it enters an increasingly uncertain climate future.

— Inayat Singh

Reader feedback

One theme that comes up frequently in reader emails is the idea that overpopulation is a major contributor to global warming.  

Nicole Mortillaro did a deep dive on this issue in 2019, and the reporting remains relevant. The main takeaways from the piece are:

  • Population is a factor in climate change, but only one of many.
  • Global birth rates are in fact declining.
  • It is key to look at per capita emissions: richer countries such as the U.S. and Canada, for example, produce more emissions per person than China or India.

To quote Kathleen Mogelgaard, a U.S.-based researcher who studies population dynamics and climate change, “Just because we slow population growth, if we continue to use coal-fired power plants to generate electricity or if we continue to cut down forests at the rate that we’re cutting down forests, those are going to be challenges regardless what the population is.”

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