How people change the environment: forests, rivers, cities and pollution
Grade 9 Social Studies Worksheet - Building Confidence
Circle the best answer.
Read this first
Card A, forest facts (FAO, Global Forest Resources Assessment 2020)
The world has 4.06 billion hectares of forest, 31% of its land. Net forest loss was 7.8 million hectares a year in 1990–2000, 5.2 in 2000–2010 and 4.7 in 2010–2020. Deforestation, clearing forest for other land uses, was 12 million hectares a year in 2010–2015 and 10 million in 2015–2020. About 420 million hectares of forest were turned to other land uses from 1990 to 2020. Net loss is forest lost minus forest gained by planting and natural regrowth. Card B, chain: people clear forest for farmland, mines, reservoirs and cities; that gives more land for crops and other uses, and less forest, which puts wildlife habitats and the livelihoods of forest communities at risk.
Noah reads the word 'deforestation' on Card A. What does it mean?
- Clearing forest so the land can be used for something else, such as farms, mines or cities
- Planting trees on land that was cleared, so that the forest area grows back again over the years
- Forest lost minus forest gained by planting and natural regrowth, counted across a year or a decade
- Any loss of forest area, including forest that is lost and then regrows in the same place later
Pia sees 'net forest loss' on Card A. What does it measure?
- Forest gained by planting and regrowth minus the forest lost, so a larger gain makes net loss bigger
- Forest lost minus the forest gained by planting and natural regrowth over the same years
- Forest cleared in a year, with the planting and regrowth left out of the count completely
- The share of the world's land that is forest, 31%, taken as a share of the whole world's land
Net forest loss was 7.8, then 5.2, then 4.7 million hectares a year (1990–2000, 2000–2010, 2010–2020). What does Card A support, Ren asks?
- Forest began growing back by 2020, since the net loss figures fell below 5 million hectares a year
- Deforestation fell from 7.8 to 4.7 million hectares a year, since the clearing slowed by that amount
- Forest kept shrinking in each decade, but more slowly each time, so the loss slowed without ending
- Forest loss ended in 2010, since each decade after the first showed a smaller loss than before
Deforestation was 10 million hectares a year in 2015–2020, but net loss was 4.7 million a year in 2010–2020. Why is net loss smaller, Tala asks?
- The two periods differ, so net loss and deforestation cannot be compared with one another
- Net loss is measured on a smaller forest area than deforestation is, so its figure comes out smaller
- Net loss subtracts the forest gained by planting and natural regrowth from the forest cleared, so it is smaller
- Net loss counts just the forest cleared for cities, while deforestation counts clearing for farms, mines and reservoirs too
About 420 million hectares of forest were turned to other uses over 30 years (1990–2020). Does that fit Card A's 12 and 10 million a year, Ari asks?
- No: 420 million is a yearly figure, so it is far larger than 12 and 10 million hectares a year
- No: 12 and 10 million a year over 30 years would give 360 and 300 million, so far from the 420 million total on the card
- Yes: 12 and 10 million add to 22 million, and the rest of the 420 million came from regrowth
- Yes: 420 million over 30 years averages 14 million a year, above 12 and 10, so earlier years had more clearing
A village clears forest for farmland. Which statement matches Card B, Bo asks?
- It loses land for crops but gains habitats, since cleared forest returns to wildlife in a few years
- It gains land for crops with no cost, since the forest is replaced by fields that feed people near the village
- It has no clear gain or cost, since Card B names the uses and not the effects of clearing
- It gains land for crops, while wildlife habitats and the livelihoods of forest communities are put at risk
Esme's note: 'The world lost 4.7 million hectares a year to deforestation in 2010–2020.' Which fix fits Card A?
- Change 4.7 to 31, since 31% of land is forest and so that figure describes the loss for the decade
- Change 'deforestation' to 'net loss': deforestation was 12 then 10 million a year, with regrowth offsetting part
- Change 'lost' to 'gained', since a figure that is below 5 million a year is a gain and not a loss
- Keep it, since net loss and deforestation both describe the forest that was cleared in those years, just under different names
Which statement about the world's forest is supported by Card A, Jun asks?
- Forest covers 4.06 percent of the world's land, since the figure given is 4.06 and is read as a percent, as the card states it
- Forest covers 31% of the world's land, which is nearly a third, so most land is something other than forest
- Forest covers most of the world's land, since 4.06 billion hectares is a very large area for forest
- About 420 million hectares, a third of the forest, were turned to other uses between 1990 and 2020
Why does a fall in net loss not show that people planted more trees, Luz asks?
- Net loss measures clearing, so a fall in net loss is a fall in clearing and has nothing to do with planting, whatever the trees do
- Net loss falls when forest is lost faster, since a bigger loss means that a larger amount is subtracted
- Net loss falls when people plant more, since gains are the one thing the net figure moves with
- Net loss could fall because clearing fell, because gains rose, or both; the net figure alone does not say which
Which claim is best supported by Card A, Milo asks?
- Clearing is the same in both periods, since 12 and 10 million a year are close enough to be treated as equal
- Clearing stopped by 2020, since the yearly figure fell between the two five-year periods on the card
- Clearing doubled between the periods, since 12 million a year in the first is read as 6 million in the second
- Clearing slowed from 12 to 10 million hectares a year between 2010–2015 and 2015–2020, but it continued