Global Change 1

About 4 million years ago, what city area was underwater due to higher sea levels?

Richmond

What factor is the dominant control of global sea level changes?

Ice balance

Approximately how much of Earth’s land was covered by ice during the last glacial maximum (~18,000 years ago)?

30%

What type of marine organisms record oxygen isotopes in their shells, helping reconstruct paleoclimate?

Foraminifera

What seafloor deposits formed by plankton shells are used to study past climates?

Calcareous ooze

What do benthic foraminifera reveal about ice coverage over the last 1.8 million years?

Oscillations

Which orbital variation occurs every 100,000 years and affects Earth’s distance from the sun?

Eccentricity

Which orbital cycle changes Earth’s tilt every 41,000 years?

Obliquity

What 26,000‑year cycle describes Earth’s wobble?

Axial precession

How many degrees Celsius of temperature change can Milankovitch cycles account for?

3–4°C

How long does it typically take for glacial melting to warm Earth by ~11°C?

10,000 years

Compared to natural glacial cycles, how much faster is today’s warming?

10x faster

What gases trap heat in the atmosphere and act as a feedback loop?

Greenhouse gases

What surface property determines how much sunlight is reflected versus absorbed?

Albedo

What is the natural stable range of atmospheric CO₂ in ppm before industrialization?

180–280 ppm

What is the current atmospheric CO₂ concentration today?

~425 ppm

Since 1970, what percentage of emissions came from fossil fuel combustion and industry?

78%

Which economic sector is the largest contributor, responsible for about 25% of emissions?

Electricity/heat

___ is favored during oceanic evaporation

Oxygen 16

___ is favored during rainfall

Oxegen_18

Orbital variations ____ cause Ice Ages; instead, they trigger pulses of advance/retreat during ice ages.

don’t