哦,亲爱的,我认为这是一个糟糕的解释图。让我们看一下标题:>黄色箭头表示年度碳通量(包括一年级)与自然的碳循环中,估计前工业时代,1750左右。粉色箭头表示人为通量平均在2010 - 2019年期间。我不认为第二句是正确的。我的解释是,粉色箭头的人为_perturbation_自然碳循环给我们观察到今天的通量。他们不代表独立的进程更明显的标记黄色的箭头。因此,呼吸和火排放总量分别为111.1热解色谱/年,1750年是111.1 + 25.6 = 136.7热解色谱/年。同样,光合作用于1750年113热解色谱/年,总值113 + 29 = 142热解色谱/年的今天,代表大约25%的增强(主要是因为二氧化碳施肥)。这符合一些文字在图5.12从较早的一份草案报告的标题:>前工业化时期以来的总光合作用的相对变化估计是基于31个±3%的范围(坎贝尔et al ., 2017)和19 land-model±12% (Sitch et al ., 2015)的估计。这是用来估计工业化前总光合作用,假设今天的范围116 - 175包括一年级(Joiner et al ., 2018)。 The corresponding emissions by Total respiration and fire are those required to match the Net land flux... Note that most of those pink values on the net fluxes row come from Friedlingstein et al (2020), who describe them as "_the overall perturbation of the global carbon cycle caused by anthropogenic activities_". Where I think this figure differs from Friedlingstein et al slightly is that it imposes closure of the cumulative 1750 to 2019 carbon fluxes (see column 1 of Table 5.1), which means that the budgetary imbalance of 20 PgC going back to 1850 is assigned to the pre-industrial land and ocean sinks. Re the oceans, in some ways this is a simpler case than the land. All parts of the ocean are continually exchanging CO2 with the atmosphere: some CO2 molecules dissolve into surface waters (entering through diffusion or bubble entrainment and collapse), and some CO2 molecules outgas from surface waters (leaving through diffusion or bubble cavitation). Figure 5.12 shows estimates of those gross fluxes in 1750 in yellow: 54.0 PgC/yr entering the ocean and 54.6 PgC/yr leaving the ocean, giving a net loss from the ocean to atmosphere of 0.6 PgC/yr. Anthropogenic emissions have perturbed the system so that there are now gross CO2 fluxes of 54.0+25.5=79.5 PgC/yr entering and 54.6+23.0=77.6 PgC/yr leaving the ocean, giving a net _gain_ of CO2 by the ocean of -0.6+2.5=1.9 PgC/yr. Both of those gross fluxes have increased because the CO2 concentrations in the atmosphere and surface ocean have both increased but, on average, the atmospheric concentration has increased more. This produces a gradient in CO2 concentration across the atmosphere-ocean interface that drives the net flux into the ocean. This gradient is maintained partly by continued fossil fuel emissions into the atmosphere and partly by physical and biological ocean processes that transfer dissolved CO2 down away from the surface into deeper ocean waters.