i have lived a thousand years chapter summaries

Because we put more carbon dioxide into the atmosphere than natural sinks can remove, the total amount of carbon dioxide in the atmosphere increases every year. Since the middle of the 20 th century, annual emissions from burning fossil fuels have increased every decade, from close to 11 billion tons of carbon dioxide per year in the 1960s to an estimated 36.6 billion tons in 2022 according to the Global Carbon Budget 2022.Ĭarbon cycle experts estimate that natural “sinks”-processes that remove carbon from the atmosphere-on land and in the ocean absorbed the equivalent of about half of the carbon dioxide we emitted each year in the 2011-2020 decade. Fossil fuels like coal and oil contain carbon that plants pulled out of the atmosphere through photosynthesis over many millions of years we are returning that carbon to the atmosphere in just a few hundred. NOAA image, based on Mauna Loa monthly mean data from NOAA Global Monitoring Lab.Ĭarbon dioxide concentrations are rising mostly because of the fossil fuels that people are burning for energy. In May 2023, carbon dioxide hit 424 ppm-a new record.

At Mauna Loa, the highest monthly value each year occurs in May. The long-term trend of rising carbon dioxide levels is driven by human activities. The seasonal cycle of highs and lows (small peaks and valleys) is driven by Northern Hemisphere summer vegetation growth, which reduces atmospheric carbon dioxide, and winter decay, which increases it. This graph shows the station's monthly average carbon dioxide measurements since 1958 in parts per million (ppm). The modern record of atmospheric carbon dioxide levels began with observations recorded at Mauna Loa Observatory in Hawaii.

I have lived a thousand years chapter summaries