The linked reference indicates there are well over 1 trillion species of microbes in the oceans and earth (mostly in the soil as indicated in the attached image). As the Earth warms-up a fraction of these microbes will likely contribute to the acceleration of carbon emissions from microbes:
Kenneth J. Locey and Jay T. Lennon (2016), "Scaling laws predict global microbial diversity", PNAS, doi: 10.1073/pnas.1521291113
http://www.pnas.org/content/early/2016/04/26/1521291113.fullAbstract: "Scaling laws underpin unifying theories of biodiversity and are among the most predictively powerful relationships in biology. However, scaling laws developed for plants and animals often go untested or fail to hold for microorganisms. As a result, it is unclear whether scaling laws of biodiversity will span evolutionarily distant domains of life that encompass all modes of metabolism and scales of abundance. Using a global-scale compilation of ∼35,000 sites and ∼5.6⋅106 species, including the largest ever inventory of high-throughput molecular data and one of the largest compilations of plant and animal community data, we show similar rates of scaling in commonness and rarity across microorganisms and macroscopic plants and animals. We document a universal dominance scaling law that holds across 30 orders of magnitude, an unprecedented expanse that predicts the abundance of dominant ocean bacteria. In combining this scaling law with the lognormal model of biodiversity, we predict that Earth is home to upward of 1 trillion (1012) microbial species. Microbial biodiversity seems greater than ever anticipated yet predictable from the smallest to the largest microbiome."
Conclusion: "We estimate that Earth is inhabited by 10
11–10
12 microbial species. This prediction is based on ecological theory reformulated for large-scale predictions, an expansive dominance scaling law, a richness scaling relationship with empirical and theoretical support, and the largest molecular surveys compiled to date. The profound magnitude of our prediction for Earth’s microbial diversity stresses the need for continued investigation. We expect the dominance scaling law that we uncovered to be valuable in predicting richness, commonness, and rarity across all scales of abundance. To move forward, biologists will need to push beyond current computational limits and increase their investment in collaborative sampling efforts to catalog Earth’s microbial diversity. For context, ∼10
4 species have been cultured, less than 10
5 species are represented by classified sequences, and the entirety of the EMP has cataloged less than 10
7 species, 29% of which were only detected twice. Powerful relationships like those documented here and a greater unified study of commonness and rarity will greatly contribute to finding the potentially 99.999% of microbial taxa that remain undiscovered."
Caption: "Fig. 2. The dominance-abundance scaling law (dashed red line) predicts the abundance of the most abundant microbial taxa (N
max) up to global scales. The pink hull is the 95% prediction interval for the regression based on 3,000 sites chosen by stratified random sampling (red heat map) from our microbial data compilation. Gray cross-hairs are ranges of published estimates of N and N
max for large microbiomes, including Earth (Materials and Methods, Approximating Ranges of N
max for Large Microbiomes). The light-gray dashed line is the 1:1 relationship. The scaling equation and r
2 only pertain to the scatterplot data."
See also:
http://www.upi.com/Science_News/2016/05/03/Study-Earth-may-host-1-trillion-species/7691462279730/Extract: "Using a series of large data sets, ecological models and global scaling laws, researchers estimated that Earth likely hosts upwards of 1 trillion species. Their models incorporated data sets on microbial, plant and animal communities compiled by governments, academic institutions and citizen scientists."