Science Stats and Dates

There are approximately this many “known“—that is, identified and catalogued—species on Earth today.

1.8 million _pg9;S1

The actual number of species on Earth today, while highly debated, is likely to be more than this many times the approximate number of “known”—that is, identified and catalogued—species.

10 times _pg9;S1

Roughly this percentage of the species that have ever lived on Earth are now extinct.

99.9% _pg9;S1

“Background“ extinction rates are now estimated to be this number (UNITS).

2 mammal extinctions per 10,000 species per 100 years _pg9;S1

Humans have greatly accelerated species extinction rates by this factor higher than the background extinction rate.

100 times _pg9;S1

Attempts to estimate species loss by relating it to the area of land that has been altered by human activity suggest that as many as this many species per this amount of time may be going extinct.

40,000 species per year _pg9;S1

According to the UN, the global human population reached 8 billion in this month of this year.

November, 2022 _pg11;S1

The global human population as of November, 2022 according to the UN.

8 billion _pg11;S1

Roughly this number of infants are born each day.

378,000 _pg11;S1

Roughly this number of people die each day.

148,000 _pg11;S1

There are roughly this number of new inhabitants on Earth each day.

230,000 _pg11;S1

There are almost a million new people on Earth every this amount of time.

4 days _pg11;S1

Until this decade, the world population was undergoing exponential growth.

1960’s _pg11;S1

While population growth has slowed and is not longer exponential, world population size will nonetheless continue to increase for at least this range of time.

50-100 years _pg11;S1

The UN projects that the world population will level off somewhere between these two numbers.

8 billion-12 billion _pg11;S1

The UN projects that world population will level off by this year.

2150 _pg11;S1

If we use the human population on Earth as an environmental indicator, it is encouraging that the rate of population growth has slowed, but we still should be concerned that the total population will continue to increase for at least this long and possibly longer.

50 years _pg12;S1

Food grains such as wheat, corn, and rice provide more than this fraction of the calories eaten by humans.

1/2 _pg12;S1

The UN Development Program reports that this percent of people live in developed countries.

20% _pg12;S1

The UN Development Program reports that this percentage of all meat and fish is consumed by people living in developed countries.

45% _pg12;S1

The UN Development Program reports that this percentage of total energy is consumed by people living in developed countries.

58% _pg12;S1

The UN Development Program reports that this percentage of all paper is consumed by people living in developed countries.

84% _pg12;S1

The UN Development Program reports that this percentage of the world’s automobiles and trucks are consumed by people living in developed countries.

87% _pg12;S1

The UN Development Program reports that the poorest this percent of the people in the world consume or use 5% or less of all meat and fish, total energy, all paper, and the world’s automobiles and trucks.

20% _pg12;S1

The UN Development Program reports that the poorest 20% of the people in the world consume or use this percent or less of all meat and fish, total energy, all paper, and the world’s automobiles and trucks.

5% _pg12;S1

For the past this amount of time, global temperatures have fluctuated but show an overall increase. Over the same period of time, atmospheric CO2 and methane concentrations also increased steadily.

130 years _pg13;S1

Virtually all scientists agree that the increase in CO2 during this amount of time is anthropogenic, coming especially from the combustion of fossil fuels and destruction of forests.

2 centuries _pg13;S1

Scientists report that over the past this amount of time, global temperatures and atmospheric concentrations of CO2 and methane have fluctuated frequently.

160,000 years _pg14;S1

From this amount of time ago until fairly recently, the global production, or mining, of lead has increased.

5,000 years ago _pg16;S1

Beginning in this year, clean air legislation required that new cars sold in the US use gasoline without lead, and gradually the same requirements were imposed in many other parts of the world.

1975 _pg16;S1

Though houses built after this year tend to have much lower concentrations of lead in paint, there are many houses built before this year that are covered with peeling paint.

1960 _pg16;S1

Peeling paint from homes built before a certain time period can be composed by this percentage of lead.

50% _pg16;S1

1 hectare equates to this many acres.

2.47 acres _pg18;S1

The number of Earths.

1 _pg20;S1

Since this year, technological improvements have increased the fuel efficiency of most cars in the US.

1975 _pg20;S1

Average fuel efficiency of most cars in the US in 1975.

13 miles per gallon _pg20;S1

The year when the average fuel efficiency of most cars in the US was 13 miles per gallon.

1975 _pg20;S1

Average fuel efficiency of most cars in the US in 2021.

30 miles per gallon _pg20;S1

The year when the average fuel efficiency of most cars in the US was 30 miles per gallon.

2021 _pg20;S1

Sport utility vehicles (SUVs), light trucks, and minivans often get less than this fuel efficiency.

20 miles per gallon _pg21;S1

Consumer preferences and personal choice for sport utility vehicles (SUVs), light trucks, and minivans, which are relatively fuel inefficient, have brought the overall average vehicle fuel efficiency down in this decade.

1990’s _pg21;S1

Mono Lake is a large, deep, and old lake, one of the oldest lakes in North America, estimated to be between these two amounts of time old.

1 million-3 million years old _pg25;S1

Mono Lake is located about this many miles in this direction relative to LA. It borders the Sierra Nevadas and the Great Basin Desert.

300 miles northeast _pg25;S1

There are this number of interconnected environmental systems critical to the Mono Lake story.

4 _pg25;S1

The net flux of sodium (Na) in the Mono Lake system per day.

5,000 mg of Na per day _pg26;S1

LA began withdrawing water from the non-salty Mono Lake tributaries in this year.

1941 _pg26;S1

LA began withdrawing water from the non-salty Mono Lake tributaries at a rate of approximately this much per this unit of time.

80.4 million gallons per day _pg26;S1

The lake level dropped by this level in 40 years after LA began diverting Mono Lake’s tributaries.

40 feet _pg26;S1

It took this long for the lake level to drop by 40 feet after LA began to divert Mono Lake’s tributaries.

40 years _pg26;S1

By this part of this decade, Mono Lake’s populations that depended on it were dying.

early-1980’s _pg27;S1

Before this year, the water system of Mono Lake was an approximate steady state with the outflow of water from evaporation more or less matching the inflow from streams.

1941 _pg27;S1

Since this part of this decade, the history of Mono Lake is an example of the interaction of environmental science with other human components like environmental policy, law, and advocacy.

early-1980’s _pg28;S1

In this year, the California Supreme Court ruled that it was the duty of the California government to protect the environment of Mono Lake.

1983 _pg28;S1

In this year, the water level of Mono Lake further increased from snowmelt in the Sierra Nevadas and the increase in in-flows from tributaries.

2023 _pg28;S1

The mean residence time of CO2 in the atmosphere.

100* years _pg29;S1

The mean residence time of methane in the atmosphere.

11.8 years _pg29;S1

The mean residence time of nitrous oxides in the atmosphere.

109 years _pg29;S1

The mean residence time of chlorofluorocarbons in the atmosphere.

100 years _pg29;S1

The mean residence time of hydrofluorocarbons in the atmosphere.

222 years _pg29;S1

The decline of the elephant population was the main motivation for the CITES (Convention on International Trade in Endangered Species) ban on the ivory trade in this year.

1989 _pg32;S1

Tsavo National Park in southeastern Kenya, which holds much of the elephant population, is a semi-arid habitat that gets less than this amount of rain per this amount of time, as a result it does not have dense vegetation on which the elephants feed.

500 mm per year _pg34;S1

A recent study by environmental scientists suggested that a viable elephant population in Tsavo, or habitats like it, would require this much area of habitat.

1,000 miles² _pg34;S1

There are this many major nature reserves in central and southern Africa that approach the required amount of habitat to support a viable elephant population.

7 _pg34;S1

There are this many major nature reserves in central and southern Africa.

20 _pg34;S1

Red spruce trees can live for more than this amount of time.

300 years _pg34;S1

Red spruce trees rarely comprise more than this percent of the high-elevation northeastern forests, such as those in the Adirondack Mountains of New York.

40% _pg34;S1

Understanding the red spruce system in the northeastern US became very important in this decade when the trees started to undergo an unexplained decline in number and health.

1980’s _pg34;S1

There had been occasional reports of unexplained red spruce death in North America since this year.

1870 _pg35;S1

In this part of this decade, multiple reports of damage to red spruce, combined with a knowledge of the relatively recent phenomenon of pollution from acid rain, led to environmental scientists to suspect that there was a link between air pollution severity and red spruce death in unusually large scale numbers.

early-1980’s _pg35;S1

Surveys taken in these two years at Whiteface Mountain in the Adriondacks of NY revealed that red spruce had decrease in population with no natural factors, such as disease or drought, that could explain the decrease.

1964 and 1982 _pg35;S1

The height of Whiteface Mountain, a peak in the Adirondacks of NY.

1,483 meters _pg35;S1

Surveys taken at Whiteface Mountain in the Adirondacks of NY revealed that red spruce has decrease by almost this percentage.

70% _pg35;S1

Surveys taken at the Whiteface Mountain in the Adirondacks of NY reveal that red spruce populations have decreased by a sizeable percentage in this amount of time.

18 years

A survey of this many mountains along a west-to-east area from NY to Maine showed that there were more dead red spruce trees standing in NY and Vermont (the western part of the region) than in New Hampshire and Maine (the eastern part of the region).

19 _pg35;S1

At the same time as red spruce death was increasing, between these two years, the combustion of oil and coal release large amounts of sulfur dioxide into the atmosphere, leading to the formation of sulfuric acid, a component of acid rain. The input of sulfate to the forest during this time period was much, much greater than in previous decades.

1960-1990 _pg36;S1

The Florida Everglades wetland is one part of a larger watershed that covers most of southern Florida and is divided into this number of connected basins.

3 _pg36;S1

The entire watershed which includes the Florida Everglades extends over more than this much area of land.

50,000 km² _pg32;S1

“Alligator holes“ are examples of small subsystems, consisting of small pools with this range of area surrounded by marsh plants, with the holes themselves kept plant-free by the activity of alligators.

2 m²-4 m² _pg36;S1

During this century, human population growth and development, and the resulting need for water and farmland, have had an impact on all the environmental subsystems in the Everglades.

20th century _pg36;S1

The Florida Everglades, once a subtropical wetland housing several bird, mammal, reptile, and plant species found nowhere else in the US is now this fraction of its original size.

1/2 _pg36;S1

The Florida Everglades once covered this amount of area, housing several bird, mammal, reptile, and plant species found nowhere else in the US.

1 million acres _pg36;S1

In this year, after years of work by several agencies (led by the US Army Corps of Engineers and the South Florida Water Management District, or SFWMD), a restoration plan for the Florida Everglades watershed was adopted by Congress.

1999 _pg37;S1

After years of work by several agencies (led by the US Army Corps of Engineers and the South Florida Water Management District, or SFWMD), a restoration plan for the Florida Everglades watershed was adopted by Congress as a part of the Water Resource Development act of this year.

2000 _pg37;S1

Current estimates are that humans have approximately this many different genes, which can combine to form a virtually limitless variety of individuals

30,000 _pg40;S2

Austrian monk Gregor Mendel was the first person to understand genetic variation within and among individual in this century.

19th century _pg44;S2

At this age, Charles Darwin became the ship’s naturalist onboard the HMS Beagle, which was about to sail around the world

22 _pg47;S2

During his journey, which occurred between these two years, Darwin made a great many observations of phenotypic variation and fitness in a great variety of species.

1831-1836 _pg47;S2

During the decades after his journey on the Beagle, Darwin synthesized his observations and developed them into a more robust theory. That theory, finally published in this year, was called “The Origin of Species by Means of Natural Selection.”

1859 _pg47;S2

Male cheetahs have this percentage abnormal sperm, meaning low fertility rates, at least among zoo populations where the most reliable studies have been conducted.

70% _pg49;S2

Bacteria appear in the fossil record as long ago as this long before the present.

3.5 billion years ago _pg51;S2

Multicellular and shelled organisms are visible in the fossil record about this amount of time ago.

540 million years ago _pg51;S2

In general, we can trace identifiable species for this range of years on the fossil record, with the lower end of the spectrum being mammalian species and the upper range being some clams and other marine species.

1 million years-10 million years _pg51;S2

The ginkgo tree, which exists in China and is an ornamental tree in many parts of the U.S., also appears in the fossil record from this amount of time ago.

60 million years ago _pg52;S2

Roughly this percent range of marine species went extinct during the greatest mass extinction on record, taking place at the end of the Paleozoic Era.

90%-95% _pg52;S2

Roughly this percent range of land vertebrates went extinct during the greatest mass extinction on record, taking place at the end of the Paleozoic Era.

70% _pg52;S2

One well known mass extinction occurred at the boundary of the Cretaceous and the Tertiary Periods, known as the K-T boundary. This is the period this amount of time ago when many species, including the dinosaurs, went extinct.

65 million years ago _pg52;S2

The tropical rainforest contains a minimum of this number of species.

10 million _pg53;S2

The area of tropical forest being cut down is about this percent per this amount of time.

2% per year _pg53;S2

During this decade, and into this century, there has been a growing consensus among biologist that the Earth is in the beginning stages of a human-caused mass extinction of species, resulting largely from the destruction of habitat.

1990’s-21st century _pg53;S2

The current mass extinction could reach the magnitude of the previous this many mass extinction periods that have occurred sporadically.

5 _pg53;S2