To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We present a timeseries of 14CO2 for the period 1910–2021 recorded by annual plants collected in the southwestern United States, centered near Flagstaff, Arizona. This timeseries is dominated by five commonly occurring annual plant species in the region, which is considered broadly representative of the southern Colorado Plateau. Most samples (1910–2015) were previously archived herbarium specimens, with additional samples harvested from field experiments in 2015–2021. We used this novel timeseries to develop a smoothed local record with uncertainties for “bomb spike” 14C dating of recent terrestrial organic matter. Our results highlight the potential importance of local records, as we document a delayed arrival of the 1963–1964 bomb spike peak, lower values in the 1980s, and elevated values in the last decade in comparison to the most current Northern Hemisphere Zone 2 record. It is impossible to retroactively collect atmospheric samples, but archived annual plants serve as faithful scribes: samples from herbaria around the Earth may be an under-utilized resource to improve understanding of the modern carbon cycle.
We summarize some of the past year's most important findings within climate change-related research. New research has improved our understanding of Earth's sensitivity to carbon dioxide, finds that permafrost thaw could release more carbon emissions than expected and that the uptake of carbon in tropical ecosystems is weakening. Adverse impacts on human society include increasing water shortages and impacts on mental health. Options for solutions emerge from rethinking economic models, rights-based litigation, strengthened governance systems and a new social contract. The disruption caused by COVID-19 could be seized as an opportunity for positive change, directing economic stimulus towards sustainable investments.
A synthesis is made of ten fields within climate science where there have been significant advances since mid-2019, through an expert elicitation process with broad disciplinary scope. Findings include: (1) a better understanding of equilibrium climate sensitivity; (2) abrupt thaw as an accelerator of carbon release from permafrost; (3) changes to global and regional land carbon sinks; (4) impacts of climate change on water crises, including equity perspectives; (5) adverse effects on mental health from climate change; (6) immediate effects on climate of the COVID-19 pandemic and requirements for recovery packages to deliver on the Paris Agreement; (7) suggested long-term changes to governance and a social contract to address climate change, learning from the current pandemic, (8) updated positive cost–benefit ratio and new perspectives on the potential for green growth in the short- and long-term perspective; (9) urban electrification as a strategy to move towards low-carbon energy systems and (10) rights-based litigation as an increasingly important method to address climate change, with recent clarifications on the legal standing and representation of future generations.
Social media summary
Stronger permafrost thaw, COVID-19 effects and growing mental health impacts among highlights of latest climate science.
Radiocarbon analysis in annual rings of a teak tree (Tectona grandis) is reported in comparison with previously published results. Samples (disks) were collected from Hoshangabad (22°30′N, 78°E), Madhya Pradesh, in central India. The previously published sample was collected from Thane (19°12′N, 73°E), Maharashtra, near the west coast of India (Chakraborty et al. 1994). Two short Δ14C time series were reconstructed with these tree samples to capture the bomb peak of atmospheric 14C and the spatial variability in this record. These time series represent the periods 1954–1977 and 1959–1980 for Hoshangabad and Thane, respectively. The 14C peaks in these places appear around 1964–1965. The Hoshangabad tree records a peak Δ14C value of 708 ± 8%, which conforms to the peak value of Northern Hemisphere Zone 3 as described in Hua and Barbetti (2004). But the peak Δ14C at Thane is somewhat less (630 ± 8%) probably due to the dilution by fossil fuel CO2 free of 14C emanating from the neighboring industrial areas. This depletion of peak values has been used to estimate the local emission of fossil fuel CO2, which is approximately 2.3% of the background atmospheric CO2 concentration.
This study addresses patterns of nutrient dynamics on a precipitation gradient (1800–3500 mm y−1) in lowland tropical forest with heterogeneous soil parent material, high plant species diversity and large changes in species composition. Mean foliar concentrations of phosphorus, potassium, calcium and magnesium decreased with increasing precipitation, whereas foliar carbon:nitrogen increased with increasing precipitation. Mean foliar nitrogen:phosphorus varied from 16.4–23.8 suggesting that plant productivity at these sites is limited by phosphorus. Total soil nitrogen increased as a function of foliar litter lignin:nitrogen, whereas net nitrogen mineralization rates decreased with increasing lignin:N indicating that as litter quality decreases, more soil nitrogen is held in soil organic matter and the mineralization of that nitrogen is slower. Extractable phosphorus in soil was negatively correlated with foliar litter lignin:phosphorus, illustrating effects of litter quality on soil phosphorus availability. Overall, the results suggest that variation in plant community composition along this precipitation gradient is tightly coupled with soil nutrient cycling. Much of our understanding of effects of precipitation on nutrient cycling in tropical forest is based on precipitation gradients across montane forest in Hawaii, where species composition and soil parent material are constant. Our results suggest that variation in parent material or species composition may confound predictions developed in model island systems.
Resumen: Este estudio trata sobre los patrones de dinámica de nutrientes en un gradiente de precipitación (1800–3500 mm y−1) en un bosque tropical de tierras bajas con material parental heterogéneo, alta diversidad de especies de plantas, y un gran cambio en la composición de especies. Las concentraciones promedio de fósforo, potasio, calcio y magnesio disminuyen con un aumento en la precipitación, mientras que la proporción carbono:nitrógeno aumenta con un aumento en la precipitación. La proporción promedio de nitrógeno foliar:fósforo varía de 16.4 a 23.8, lo cual sugiere que estos sitios tienen limitaciones de fósforo. El nitrógeno total del suelo aumenta como una función de la proporción de lignina foliar de la hojarasca:nitrógeno, mientras que la tasa de mineralización del nitrógeno neto disminuye con un aumento de la proporción de lignina:nitrógeno, lo cual indica que mientras la calidad de la hojarasca disminuye, más nitrógeno del suelo es retenido en la materia orgánica y la mineralización de ese nitrógeno es más lenta. El fósforo extraíble está correlacionado negativamente con la proporción de lignina foliar de la hojarasca:fósforo, lo cual ilustra el efecto de la calidad de hojarasca en la disponibilidad de fósforo del suelo. En resumen, estos resultados sugieren que la variación en la composición de plantas de una comunidad a lo largo de este gradiente de precipitación tiene un efecto considerable en la retroalimentación de los ciclos nutricionales del suelo. Gran parte de nuestros conocimientos sobre el efecto de los gradientes de lluvia en ciclos nutricionales del suelo han sido basados en estudios de gradientes de precipitación de bosques de montaña en Hawaii, en donde tanto la composición de especies y el material parental del suelo son constantes. Nuestros resultados sugieren que la variación del material parental del suelo y la composición de especies pueden confundir las predicciones desarrolladas en sistemas modelos de islas.
Email your librarian or administrator to recommend adding this to your organisation's collection.