The legally binding international agreement to reduce greenhouse gas emissions is known as the
Which of the following is INCORRECT?
Scientists can definitively (100% certainty) attribute climate changes to anthropogenic causes
alone.
Increased atmospheric carbon dioxide (CO2) causes warming temperatures.
Global warming affects overall climate.
Human activities have increased the amount of atmospheric greenhouse gases.
Which of the following accurately describes 13C/12C ratios of plant materials and their use in
climate reconstructions?
Different plants use different types of photosynthesis, each producing a different carbon
isotope ratio in plant materials, which scientists use to determine past temperature and
rainfall conditions.
13C is an unstable isotope, which decays at a constant rate. This is used to date plant material,
which can then be used as a proxy for temperature and climate conditions at that time.
By analyzing the ratio of 13C/12C in marine phytoplankton, the source of the water in which
the organisms resided can be determined.
12C is very rare in nature. When it does appear in plant material, it is indicative of climate
anomalies. By measuring the 13C/12C ratios, scientists can determine whether the plants were
alive during normal or anomalous conditions.
Scientists use ________ to study past climates, using ________ to reconstruct climates that extend
back further than our present instrumentation allows.
direct measurements; historical records
proxy methods; climate proxies
indirect evidence; conjecture
computer models; algorithms
D